create widget . add putons like low / med / epic and just create node execute console comand and write like sg.shadowquality 0.1.2.3 etc.
https://docs.unrealengine.com/4.27/en-US/TestingAndOptimization/PerformanceAndPr...
or
use this note for setings
https://answers.unrealengine.com/questions/988523/question-about-get-game-user-s...
(0-low/1-medium/2-high/3-epic/4-cinematic)