There is one side quest in Rimmen that requires you to have reached a certain point in the main quest before it will appear. It features a base game NPC and takes you (in part) into an area that has to be unlocked during the main quest, hence the prerequisite.

I’m not familiar with any others, though they may exist.

There are a few of them. Most of these turn up either after the main quest or after you have done the quests in the immediate vicinity

Some I know are as follows, one near alinor north west gate, shadowfen has a couple right down the bottom of the map also companions hall in north east corner of the rift

I use an addon, think it’s called quest map, once it’s set up it shows everything, regular updates recently, has a few issues such as showing you quest markers for quests you can no longer do due to something you already did, ie quests to get you to go to certain areas, but it’s a great way to find these subsequent ones

Also the one near alinor is brilliant, one of my favourite stories even if it’s quite short 🙂