Set C4D to (Display > Units). Realism requires real-world scale.
If you are looking to acquire legitimate licenses or explore the evolution of this product line, you can visit the Official Chaos Website or read community hardware benchmarks on the Chaos Forums to see how V-Ray scales on older vs. newer Windows workstations. Chaosgroup Vray for C4D 3.6.0 R18 to R19 Win
Use the V-Ray Frame Buffer (VFB) instead of Cinema 4D's native picture viewer. The VFB allows for direct color correction, exposure curves, and history tracking on the fly. Set C4D to (Display > Units)