FSR RCAS Sharpness in stops (0: sharpest, 1: 1/2 as sharp, 2: 1/4 as sharp, 3: 1/8 as sharp, etc.). A value of 0.2 would correspond to a ~0.87 sharpness in [0-1] linear scale
Usage
r.Mobile.FSR.RCAS.Sharpness [value]
Set via the console (~) or in DefaultEngine.ini / DefaultGame.ini.