Tessera is a Unity addon for procedurally generating 3d tile-based levels and builds.
Tessera works by running the Wave Function Collapse algorithm. This algorithm is a powerful technique for generating maps from complicated tile sets with tight controls on behaviour.
Tessera is available on the Unity asset store as two different packages. The basic version includes the fundamentals of generations and key features, while the Pro version contains more advanced features. These tutorials cover both, with pro-only features clearly marked.
Tessera has a lot of features. Try the following links for tutorials and an overview of what is available.