Limiting full screen size

I want to limit the full screen size of my packaged project to a specific value, and not to the maximum value of whatever screen the game is being played on. My monitor on one computer was set to a very high resolution and the game was lagging in full screen. I have optimized it as much as possible by the way. I want to limit the full screen size to only displays scaled pixels of 1K or 2k. Essentially making the full screen default of my game what I specify and not the resolution of the players monitor. It would also be nice if it could be full screen and not windowed right when I start the executable. I’ve searched for this and haven’t been able to find a solution. If anyone has tried this before or has any suggestions that would be greatly appreciated. Thank you.

Once the game is packaged, you have total control over the screen size modes. In fact, you have to specifically program it.

One thing you could do, is let them run in full screen, if they want, but give them the option to change the resolution scale:

This way, it can run full screen, but it’s only using a certain % of the pixels it would normally use.