Is your feature request related to a problem? Please describe.
I have a 1050 Ti, a fairly low end graphics card that isn't exactly the best for running shaders like Complementary at a stable 60 fps on default settings. However, the render scale option lets me sacrifice rendering quality for performance which I really like. The shadow quality option could let me downscale/upscale shadows further than what the shader supports, for example, SEUS PTGI is a shader where you can't change the shadow resolution. This would allow shaders to run on incapable/lower-end machines at a much higher framerate.

Describe the solution you'd like
Have two buttons like with OptiFine to control these settings on the shader menu.

Describe alternatives you've considered
Fast graphics

Additional context

OptiFine menu

Possibly it could look like this:

Being able to type a custom value in instead of tapping the button over and over to get the setting you want would also be great

Iris is purely a shader mod and doesn't generally cover additional features that Optifine, which is a kitchen sink of client features, may include. ResolutionControl+ is a separate mod that gives you this particular feature. Further Optifine features are implemented by the mods listed on this page: https://lambdaurora.dev/optifine_alternatives/

duplicate of #757

Tested ResolutionControl+, it is pretty nice but the linear downscaling method seems to be a bit worse than OptiFine's

Can't close this so it will remain open until someone closes it