Are there any good autotiling tools or tutorials for procedurally generated tilemaps?

So I'm starting a project that procedurally generates a world using perlin noise. I'm looking for a tutorial or a simple way to have the tiles of the world autotile. I've read ways about bitmasking, but I am having trouble finding good tutorials to do 8-bit bitmasking because I want the corners of my tiles to be rounded. Is there any built in unity feature or something that can do what I want?