In-game graphic setting for low platform gamer?

I just upload my games prototype to my team and I am only one who have powerful PC in my team… They all use low platform pc ( plus one Mac user, I can’t show that prototype game to Mac user… )

Most of them unable to play smooth just like my PC can do.

That mean I have to expecting most of my customer will have low - medium platform computer…

How can I set up brightness and graphic setting in game’s main menu for this problem?

Only via C++

In blueprint you can only exec commands in console, all rendering related commands start with “r.” prefix

Ta. Look like I have to learn more about c++… I have friend who have knowledge in c++ but not game play… Is it worth to ask him to help me out even if he had no skill in games?