Mod generating the world with three layers of stone

[Infine]

How to do it?

In the picture, a layer of stone, other stone and shale.

[ChampionAsh5357]

First, this is not three layers of stone. There is stone and deepslate, which are each two separate biomes in most cases. The shale is most likely a feature. However, in general, you can either create three biomes each with differing depths so that they may be stacked on one another or you can use features to replace blocks within a certain area based on certain rules.