Flowscape is a surprisingly powerful environment creation app, and it's only $10! For that $10 you get a ton of assets including; terrains, foliage, animals (animated!), atmospheres, and effects (rainbows, rain, snow and more). Since it's built on the Unity Engine you also get to control and animate almost all of the elements to create any number of scenes. I spent some time with it a few months back:
https://vimeo.com/394353050 These scenes rendered out at 4k very quickly, less then 3 seconds per frame. The Australian developer has promised an upgrade in the near future and it looks like some cool things are being added. If you've ever wanted to explore the Game Engine universe, this has to be a great starting place.
https://pixelforest.itch.io/flowscape
