im trying to make an editor for my game. but I want to know is it possible to edit terrain map heights or textures? if the answer is true, should i make it from scratch or can I use unity editor tools in real time? is there any asset for it? thank you for helping
Yes, it is possible. Take a look at the classes Terrain and TerrainData. You can edit the heights with the method "SetHeights" by passing float arrays. But it can be very expensive, depending on what you exactly want to do.
There are several Tutorials all over the web, covering this topic.
This answer is a bit vague, but your question is not very specific what you exactly want to do. But in fact it is possible to manipulate the Terrain in realtime as user.