From what I am reading the Asus VivoBook Go 15 does not have an adjustable size UMA buffer. However you can check.
Power off the laptop.
Press and hold F2 while powering the laptop on.
Look for UMA Frame Buffer or reference to Graphics Memory in the BIOS.
Check if the size is selectable.
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT
Ryzen R7 5700G | B550 Gaming X | 2x8GB G.Skill 4000 | Radeon Vega 8 IGP
Ryzen R5 5600 | B550 Gaming Edge | 4x8GB G.Skill 3600 | Radeon RX 6800XT