Worldbuilding in the Unity Editor
Now part of Unity, ProBuilder is a unique hybrid of 3D modeling and level design tools, optimized for building simple geometry but capable of detailed editing and UV unwrapping too.
Use ProBuilder to quickly prototype structures, complex terrain features, vehicles and weapons, or to make custom collision geometry, trigger zones, or nav meshes.
ProBuilder also takes advantage of Unity’s seamless round-tripping capabilities with digital content-creation tools (like Maya), so you can further detail and polish models with your favorite tools.
Getting started with ProBuilder
Get ProBuilder
ProBuilder is available from the Package Manager and is compatible with Unity 2020 LTS and later.
Documentation
Refer to the documentation and check out the tutorials.
Other worldbuilding tools
Be sure to check out Polybrush.