Its a bit hard to described what I mean with "world building", but basically what I am looking for is something where more than Voldemort happens in plot...
The in my opinion best example would be "The Good War", where you have lots of additional stuff going on (its also still updating regularly :). Maybe also in Rigel Black.
The only thing I find important is that its really really long and preferably finished or updating regularly, going over multiple school years.
Romance can be included, but should not be the main plot please. The examples I gave are fem!Harry, but thats just a coincidence, not a requirement.
Edit: Basically all fics that are not totally copied from the books (plot wise) and include many school years are welcome. Because even that is something I struggle to find