The level of the other players in the group should be irrelevant since the dungeon does not scale to the player's level. Every NPC in the game is CP160. While I cannot answer if there is a change to the wstats of a character when they enter a dungeon, it will not give you more health (or tanking attributes) because you are listed as a tank.

I am a relatively new player in ESO. I also recently leveled a tank. I quested to get skill points for a while, then crafted fresh gear and did PvP for a while to get my WH and finished up-leveling in dungeons. I started the dungeons a little after level 40 and it was during a double XP event and we did a lot or randoms to level our characters. I will note that I forgot to change my attributes or CP for tanking but it was not an issue. I did just fine but after I correct it I did find things a little easier.

Good luck.

characters from level 1-50 do have a scaling buff, that gets weaker as you approach 50 (this is because all of the enemies are basically cp160, and it is scaling you UP to the enemy level, but this scaling bonus gets weaker and is fully gone once you hit 50)

right around 25-35 is the time this becomes significantly more noticeable and is where you will start to notice your stats (hp/mag/stam) get weaker

another thing to keep in mind is that your gear will also scale down if you are over leveled for it (using level 20 gear on a a lvl 30 toon, you will be getting smaller buffs from the enchantments and armor/dmg values)

generally speaking if your not rushing to 50, you want to try to keep your gear within 5 levels of your current toon, and as you approach 30s-40s in level, everything is going to feel a lot harder unless you are using crafted set gear

basic rule of thumb if you want to tank is make sure you have a taunt, and try to keep your armor buffs up, you want your armor with buffs to be probably a minimum of 25k but 33k is the armor cap for the maximum 50% dmg mitigation, usually 1h+shield is a good way to get there to practice (and having a shield gives you extra armor)

there are some buffs that do increase max hp (minor toughness for one) as this is +10% max hp, which can easily be granted by warden

i think warhorn can also buff stats, but do not know off hand if it uses minor toughness, or its own unique buff (for stacking purposes)

there is also a mythic that increases stats in combat (death dealers fete), but you wouldnt be able to use that until you were already cp 160 anyway (so im discounting this since you were on a lower level toon, was just including it for reference)

other ultimates as well (such as necromancer goliath, or the vampire ultimate) can also increase stats (goliath is +30k max hp during effect, vamp scion is +10k to all stats during effect), im not sure if you were using either of these, again just including for reference

that is what i would do, respecing attributes is very cheap (and you get 1 free attribute respec scroll from level up rewards to do this anyway)

ideally for a tank you would want to aim for 33k resistance, around 35-40k hp without food (there are debates about this, but i think 40 is a good starting point)

if your going the 1h/shield route for tanking, then i usually try to also aim for at least 20-25k max stam, and anything to reduce block cost/increase amount of dmg you can block is very helpful (block can be triggered up to 4x per second, so reducing the cost will greatly help when you need block for long periods of time)

there are plenty of ways to get more armor (since you need to include your buff skills in that)

major resolve should give you approx 6000 armor
there is one red CP slottable that gives around 1750 armor at 50 points invested
you can also get the lady mundus stone (which is around 3000-4000 armor, depending on how much divines you have, although as a tank, sturdy is a pretty good trait for reducing block cost)

and using mostly heavy armor (at least 5 pc) should put you around 20k base armor

you also mention igneous shield so im assuming you are also a dragonknight

you should be regularly applying your armor buff (base skill is spiked armor), if you get the morph hardened armor it will give you the armor bonus as well as a dmg shield that scales on your max hp

to give you an example my main toon is a DK and im sitting at around 25k armor without any buffs running, i have 5 heavy and 2 medium armor, and the lady mundus stone (with my armor buff running im at just under 32k armor, i could probably get up to around 33k but i would have to finish golding the rest of my armor lol)

if you needed extra help, there are other sets which grant additional armor as well (lord warden monster set is a good group buffing one)

one that would make it even easier is something like almalexias mercy set (light armor but good weapons and jewelry set, it grants max hp, 2 armor bonuses, and when you take dmg every 3 sec you do an aoe heal over time) (there are a lot of options that will work here depending on what your end goals are)

@Necrotech_Master

Ran Elden 2 yesterday, (lvl 38) and noticed something on this scaling thing.

My pre-dungeon health was high 39k or something, and while fighting the last boss I noticed it was way up at 48k or something like that.

I did not buff anything but there was a healer in the group that was CP1100 or more. And, at the start, I was assigned the crown, and being focused on learning tanking, I "yelped" and reassigned it to this healer (sometime early in the dungeon).

But there have been other dungeons where my health does not change. Gotta presume it has to do with something about the group level spread and/or the level of the crown. For all I know, if I kept the crown, my health would not move and perhaps the bosses might be a bit softer.

I was a good practice though on the final boss.

@Necrotech_Master

Sorry, I forgot to mention. Changed gear, as I was up to lvl 38 and as my gear and my Warrior Poet stuff (where the 10% bump came from, I think) was down at lvl 30.

On Elden 2, was running Jolt (tempest), Ebon (crypt), and Plague Dr and coincidentally, no one set was at 5 pcs. And I know that I did not use any food or drink buffs.

As you mentioned all this goes away after lvl 50, but for the next while, I am going to pay particular attention to this feature. For instance, on that one dungeon, got 5 pieces of Undaunted Bastion, which seem decent, but the pieces I got will create a bit of a odd mix with the other pieces I am running. So, I will likely be running it again to farm some stuff.

To your offer, thanks. I am inclined to take you up on that. I am on PC-NA - pacific coast- and for most of my time with the Elder Scrolls franchise been on console (Skyrim, etc) and only got into ESO about a year ago. Even then, running solo - not guild connections etc.

I have been toying with the idea of somehow finding a guild or someone in the community to run things with, as there seems to be a lot more to the use of this game than I thought, and likely need that to help learn the finer points.

Have not even figured out the keyboard techniques of trading at the end of dungeons. Only got taught the other day on how to pass the crown to someone else. While running Scalecaller, as we were waiting for a 4th to show up, one character on the screen was sitting in a chair waiting...that was hilarious. Til I found out the keyboard commands to do things with your character.

So it is growing on me just how much there is too learn in this game.

If the times and circumstances match, how would we connect up? I sometimes do things at the end of day (evenings) and routinely do things. I know that I had someone - in game - ask to be a "friend" and now I get sort of notifications in the bottle left (in a different colour - white or yellow or something), when they are online. Or does this forums thing allow for a type of text msg?

@Necrotech_Master

Trying to think this thru. Since you are on before me, a way to let you know - when I get online - that I am there, would be best.

I remember there is this group invite thing I noticed once or twice. That way, when I am in the mood for dungeoning (vs harvesting or treasure chest hunting or something, I can send some invite?)

I do not know how it shows up on the receivers end, but it could be worth a try this weekend.

I have never even tried doing this before, so if you know of a different way