Settings /about phone/software information
Scroll down to 'build mode'
Keep tapping that until it says developer mode turned on (about 7 taps)
But only do this if you know what you are doing.
Any changes could seriously screw up your nice new phone
Been using developer options for years and I've never seen a setting called "force GPU I to overdrive", have I been missing it all this time, or is it a setting that is new to the Note9? I'm still using Note 8 and I have no such setting.
Force GPU rendering
Turn off hardware overlays
Always use GPU for screen compositing
Second option must be turn on after every reboot, it switches off everytime you power off your phone
I don't use third GPU tweak, as called turn on 4x MSAA sth antyalias for graphics but makes stuff looking to soapy to my eyes