This is rather the task of a sculpting program and I don't think you could it easily in MAX.
There is a chance to do using a basic poly structure and then adding displacements as here. But it is easy to lose the control of the global look:
https://www.youtube.com/watch?v=sJyNMrZps0o
Once you have several pieces like these you can combine them to create a more complex space.
This would be the workflow using Zbrush, where apart of simply sculpting we can use Alphas as displacement but in a more free way that you would do in Max as you are not limited to UVs, you "paint" the 3d shapes in the mesh.
https://www.youtube.com/watch?v=gG-mEnP-9OI
You can find easily rock alphas in this google link: Alpha rocks
There are free alpha rock libraries and very cheap ones rocks brush set
https://gumroad.com/l/jqTc
https://gumroad.com/l/nFLGX
Finding a good real rock wall and doing 3d scan would be a good workflow, but would involve knowing several complex techniques (photo, 3d scan, zbrush etc)
Finally there are some 3d scans rock scenes that can be downloaded and used free of cost with some conditions. Normally author must be credited, and many allow commercial use. See the conditions in each one:
https://sketchfab.com/magadan/collections/nature-pack?cursor=48
But combining them together in a coherent way needs knowledge of Zbrush and 3d in general as it is easy to get lost with 3d scans, lighting stored in the textures can be an obstacle etc. Keep in mind that many games now are done with these kind of 3d scans as base. Obviously they scan their own rocks:
