For viper4android use this method :
install apk from this link https://forum.xda-developers.com/android/apps-games/app-viper4android-fx-2-6-0-0-t3774651
don't open the app yet
download zip file from this link and flash it through twrp...
It works perfectly but i have a small problem... When i open 5 apps for instance and when i want to switch between them it switch from app number 1 to number 2 then return to number 1 and switch again to number 2 then it switch perfectly to app number 3,4 and 5 respectively... So why it repeat...
There is no relation between DC Dimming and android version because One Plus 6/6T got it with the last update and the two phones still in android pie....So it can be possible that we can get the feature in our phone before getting update Q .