How i can do the low,medium,high, epic and auto button via blueprint? Is there a console command like “sg.EffectsQuality” for doing that?
Yes there is console commands for all of the settings. I don’t remember them all off the top of my head but if you check out the Virtual Reality character template available off the forums here they have an in game menu that allows you to tweak all of the values so you can just grab them out of there.
edit: sorry I didn’t understood what you wanted. Can u explain a bit more please?
scalability 0-3 (0=Low, 1=Medium, 2=High, 3=Epic)
scalability auto (don’t know if this works in a built project)
If you’re curious about more commands you can open the Output Log and type “DumpConsoleCommands”, after that you can just write “scalability ?” to get information about said command.
This is quite simple if you know the commands. 
Look:
To do it properly i’d use the GameUserSettings class. Explore that! there’s all kinds of ■■■■ in there.
I’d definitely use this approach over just using the scalability 0-3 presets. This gives you the ability to customize individual settings. Also, if you truly need to hammer in some custom settings, you’ll probably want to manually design a bunch of presets where you can tweak obscure cvars like all of the individual shadow settings and so on. But for the most part, all of those can be changed in console anyways. Just saying that you can deviate even further away from generic “one size fits all” setting levels.
Where is this class?