The Rock
Here I start to sculpt my rock in ZBrush and then I decimated it into 300k mesh. I remesh the main rock into 35k tris rock and in Maya I use reduce polygons option and reduce it to 11k tris.
I use the 300k rock as high poly rock to be baked on other 2 versions of my rock and textured them using Substance Painter in 2048*2048 texture size.
I Render these using ACES in Substance painter and some tweaking some effects.