This is a paid asset, but now you can download MapMagic 2 Biomes and Functions for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
MapMagic 2 Biomes and Functions v2.1.10
The official module of the MapMagic 2 (free) world generator. Allows blending of the several graphs basing on a mask, this way allowing to mix different biomes on one endless terrain. Also includes Function nodes, that allow to take out the complex generate process in a sub-graph. Think of them like of biomes that has input and output connectors.
Note that an existing installation of MapMagic 2 is required in order to use this module.