Sadly that setting seems like just there to annoy people
I literally tried setting to 0 GB for LULZ but it did not have effect. It seems to be a placebo setting that actually does nothing, because frames kept dropping at 4K despite being set to literally 0 GB
As i said countless times before, there's no world where you "dial down" textures and get away. You either have enough VRAM... or not. This was the same case with Godfall.
Going from the highest possible textures to lowest possible usually only brings a funny 100-500 mb of vram at best that will probably be filled with other stuff in-game anyways
I had been there with a 2 GB card in 2017. No game functioned properly, ever. Even with lowest possible settings, being out of VRAM still hit the performance. No amount of low resolution, no amount of low textures helped with the performance hit.