Are there any other shows that can compete with those two's worldbuilding?

I didn't watch HxH and One Piece so I can't really compare against them, but my favourite worldbuilding is from Cells at Work!.

The bodily functions are presented in a way that dumb things down sufficiently to the viewers while still largely retaining scientific/medical accuracy.

Honourable mention goes to the Umamusume franchise. The level of details that goes into building a world that is almost exactly like ours - except with horsegirls instead of horses - is more than I'd expect.