Last September, we unleashed AMD FidelityFX™ Super Resolution 3 (FSR 3)1 on the gaming world, delivering massive FPS improvements in supported games. AMD FSR 3 is the latest version of our cutting-edge open upscaling technology – adding advanced frame generation technology for significant framerate ...
For FSR to work best it has to be built into the game. There are ways to make it work without it but it’s not as good.
So to upgrade to later versions the game developer has to do it.
Tho unlike Nvidia’s DLSS FSR doesn’t use dedicated hardware and you can run it on basicly any modern GPU.