Animal crossing procedural land.

I've been trying to figure out, how exactly they do it. But everywhere I turn, it's either that it's to hard or the question isn't answered. Because I've made assets, but I don't know how I should export them or set them up in unity. I know I can use terrain but it's not the style i'm going for. So in total I have a mountain small cliff and river. so three states that need to be randomly generated any and all help would be appreciated.

 

It might be helpful to get a bunch of blank 3x5 cards and cut them to be square (3x3 size).

Now mark (or color) a few as mountain, cliff and river, and see how you can combine them physically side-by-side and start to get an idea of how you want to handle transitions.

With some constraints you won't need every possible combination transition, and to start with, you want to keep it simple, with as few combination possibilities so you can grasp them all at once in-brain.