Have MacBook Pro with 4GB Video RAM, can only use 2GB of that.

Not sure if I'll run into a situation where I need all 4GB of my Video RAM, but the configuration interface is only letting me use 2. I guess by using those 2, macOS has 2GB Video RAM and the VM will have 2GB? So like, assigning all 4GB for some relatively new game or 3D editing program would mean macOS wouldn't have any, so I guess that's impossible, but...what about like, 3GB/1GB? Is there a way to use more than 2GB Video RAM? I'm using the regular version Parallels sells for $79, which also has the limit of 8GB RAM, and the Parallels Desktop for Mac Pro for $99/yr doesn't have that limitation, but would it also let me use more Video RAM?