World building for other worlds

Personally, my campaign has a lot to do with visiting very weird planes of existence. I would absolutely love some world building features for weird worlds. Examples(D&D5e):

Mechanus – A world where everything is mechanical. The floor are gears, the sky is not there but is also gears. Mechanical world.

Air Plane – No ground, just clouds to walk on or fly.

Water Plane – Everything underwater.

Shadow Realm – Dark gradient on everything. Like a black and white movie.