Not from usual source but here's some Starfield performance numbers:
https://www.digitaltrends.com/computing/starfield-pc-performance-best-settings-fsr-2/
For some reason, they didn't test a 4090. Also it appears 8GB of Vram is enough even at 4k Native + Max Settings. No Stutters or anything. Surprisingly well optimized for a Bethesda game.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850