This video tutorial goes through the steps to creating rocky landscapes using displacement maps in VRay for Rhino. The textures used in this video tutorial can be found via https://polyhaven.com/
The key steps in this tutorial can be found below:
0:28 - Finding rock texture maps
0:46 - Creating a generic Material
1:00 - Setting the 'Diffuse' colour using the rock texture map
1:44 - Applying the texture to a surface
2:04 - Texture mapping and adjusting texture size
3:10 - Adding in a 'displacement map' to change an objects geometry
4:26 - Adjusting the 'Amount' value of the displacement map
6:30 - Using atmospheric lighting to emphasis displacement textures