What happens if you combine sg.ShadowQuality x with raytraced reflections in a PostProcessVolume?
By default probably nothing but you can make it set whatever you want.
If you’re asking whether scalability shadow settings will override the post process volume, it depends on what r.RayTracing.Reflections.Shadows is set to. By default it is set to -1, in which the post process volume determines what the reflection shadow is set to. Setting it to anything else seems to just ignore the post process volume setting from my quick test but you should probably test it yourself to verify.