Texture quality as in what resolution they are, the reslution you play at, texture density, texture filtering (very little), anti aliasing (like MSAA not post process stuff like FXAA) or supersamling, render distance, amount of things to load at one time (like uGridstoLoad value in skyrim or fallout), tessellation, ambient occlusion, honestly most optional graphics options will increase VRAM in some way. I would say the biggest contributors are resolution, anti aliasing, render distance, and texture quality.