Material Blending Depth and Mask Adjustments

I was wondering how someone would go about layering a blended material in a more convincing way. I would like to get the depth seen in the last photo, where the plaster is further out than the layer beneath it. I can do this with tessellation, but I was wondering if anyone had a more performant way of simulating this. Also, I was curious if there is a way to break up the vertex painted mask to get something more jagged for the transition between the two materials.