Problem with Resolution/Scaling/DPI on iOS

Hey guys, I'm about to release my game for iOS devices, it is a graphic-intense game, so it runs slowly with devices' native resolution (9-20 fps), so I want to run it in half of that device's native resolution, however, there is no such an option in Unity. I tried to make use of "Resolution Scaling Mode" and "QualitySettings.resolutionScalingFixedDPIFactor", but it doesn't work on iOS. The problem with "Fixed Target DPI" is that for example: value of 132 means half of iPad resolution, but it means almost one third of iphone 6-7- 8 and almost one forth of iphone X series, which leads to huge loss of quality. Does anybody have any idea how to resolve this problem? Thank you.

 

NVM, Screen.SetResolution() gets the job done