how to increase resolution while in game to higher resolutions than the GUI allows

[ThisIsMyDogKyle]

so with the new feature that allows you to get screenshots at the internal resolution on certain backends I was going to try and get some absurdly high res screenshots, my only issue is that the game runs at like 1.5 FPS so I figured I would just change the resolution once I got somewhere I wanted a screenshot, only problem is it seems you can only change it to one of the predefined resolutions in the drop down menu once in game and as far as I know the only way to get above these is by changing EFBScale in the games config file, but you can't change that in the middle of running a game, is there any way I can add my own custom resolutions to the drop down menu, or input a command to do this? Thanks!