Hello there,
I am currently creating my own custom settings object for saving custom properties such as gameplay relevant stuff and so on. Additionally I just want to let the user choose the desired gamma level of the entire game (e.g. for ■■■■■■ dark screens). I have found the console command
GAMMA float
does that for me. The default value is about 2.2.
But nor I want to implement my “ApplySettings” method in a much more elegant way and I try to avoid calling console commands in my C++ object (which btw inherits from UGameUserSettings class).
Maybe you guys can help me finding the property or setter that I have to use to trigger the change of the gamma level via C++? Any ideas? I do not have any clue where I should start searching. 
Greetings,
Dustin