I believe the reflex part of this will mainly work for Nvidia users, however the framegen will work with AMD and Nvidia cards.
To enable frame generation head into:
C:\Users\your computer name\AppData\Local\SilentHill2\Saved\Config\Windows
Open engine.ini and go to the bottom, then paste the two following lines:
[SystemSettings]
r.FidelityFX.FI.Enabled=1
Hit save and download RTSS:
https://www.guru3d.com/download/rtss-...
Add the silent hill 2 exe into your RTSS, then make sure you head into setup and select reflex as the frame limiter.
Start your game and select FSR3, you should immediately see that this will enable Frame Gen, although it might crash so beware of that.