Locate Game.ini and GUS.ini
Both Game.ini and GameUserSettings.ini are located in,
Filepath may differ a bit.
On dedicated rented servers, the file path can differ quite a bit. Generally, they can both be found at a similar location like this(Nitrado),
Remember to exit your singleplayer game and your server before editing these!
In some cases, single-player ini’s can have permission problems, they can be set to read-only, or your game overwrites the ini after you’ve started it. Check file permissions if your changes won’t work.
Similar for rented dedicated servers, where they can offer a GUI they created themself, they can offer you to edit the ini through your browser, or you can have FTP-access to edit the files directly. Check with your provider!