On norm, maybe. There have been a few that have soloed on Vet, but you really don't want to know what was involved to do so, and that was prior to multiple nerfs.

Most of the new ones will have at least one mechanic that will require group synergy. After all, they're intended to be group dungeons.

If you're truly curious, buy ESO+ for one month, or wait for a free trial, and you can set foot in any 4 man content in the game.

To be perfectly honest, unless massively on sale, it's hard to justify outright purchase of any Dungeon only DLC, even if you're running with a group.

They're neat, but unless you're motif, gear, or achievement farming, you really won't run them as often as you think.