Mods that add Morrowind/Oblivion style dungeons etc. ?

[Tinxi]

Also, how to craft mod-added buildings in skyrim ?

[Varithina]

Have a browse through these lot and see what interests you, if you have not already done so anyway, https://www.nexusmods.com/skyrimspecialedition/mods/categories/88/?BH=0

 

I have hammets dungeon pack https://www.nexusmods.com/skyrimspecialedition/mods/12186 I use the esm version though there is or was a esp version as well, forgotten dungeons https://www.nexusmods.com/skyrimspecialedition/mods/449 and easyriders dungeon https://www.nexusmods.com/skyrimspecialedition/mods/2218, packs installed, but not really explored them all that much, though I should.

 

Edit, crafting dungeons is not easy, ck is a pain to work with at times, and the main problem from what little I do know about it is not building the dungeon, it is the navmeshing which is a major pain in the but to do, I have re navmeshed a couple of mods from fallout 4 and they were a major pain, as if done wrong you end up with npc's not doing much as they can not path to the player or worse spawing in walls and not being able to leave due to having no pathing to leave by. 

 

Maybe have a watch of this and any of the same series

Spoiler