You cannot increase iGPU VRAM beyond 2GB on Hackintosh. However, you can stabilize it. For a "new" build, you must enter your BIOS and set:
Essential for all graphics patching in Hackintosh. uhd 770 hackintosh new
Unlike the legendary UHD 630 found in 8th, 9th, and 10th gen chips, the UHD 770 presents a new set of challenges and requirements. If you are searching for "new" information, here is the current reality of running this iGPU on macOS. You cannot increase iGPU VRAM beyond 2GB on Hackintosh