Interesting carpets: https://3dsky.org/user/favorites/models_collection/5439437 
The volume is executed using Displacement.
For the Displacement to work correctly, enable its display: Common -> Options -> Displacement. To detail the volume, go to the Perfomance -> Displacement -> Screen size(px)=1.5-1.7
https://www.rodwellandastor.com.au/products/nebraska-floor-rug-natural-white