How to render at true full screen resolution in Unity? (ex. 1080p on a 2560x1440 monitor)

We are making a Pixel Perfect game, with a reference resolution of half 1080p (960x540).

My monitor is 2560x1440, so I have three options.

1. Choose 2560x1440, have the camera render at 1080p scale with blackboard for the extra pixels
2. Choose 2560x1440, and select "Stretch Fill" on pixel perfect camera
3. Choose 1920x1080

However, I noticed the issue is that #2 and #3 are exactly the same.



The reason why, is because even when I choose to start the game at 1080p, it actually starts the game at 2560x1440 and Stretch Fills from 1080p. There is absolutely no difference.

I checked my monitor, and even when I select a different resolution, it never actually changes the monitor's resolution. It's always 2560x1440, no matter what I select. I remember reading about DX9 & "true full screen", and the difficulty of this in Unity (which loves borderless windowed mode).

I noticed in some modern games, like Witcher 3, changing the game's resolution also doesn't change the monitor's resolution. Windows desktop is the same way. I loaded an older game (City of Heroes) and it actually changes the resolution of the monitor to whatever I set in the game.

Is it no longer possible to do true full screen for modern games (something with Windows?) Is the only option to revert to an older version of Unity which uses DX9 (bc this is deprecated now)?

Also related: No pixel perfect rendering when at lower resolutions, despite pixel perfect camera

https://forum.unity.com/threads/no-pixel-perfect-when-at-1x-zoom-only-when-at-2x.875419/

 

I am working off of very old knowledge from my work in Unity 5 & the awfulness that is Unity defaulting to Fullscreen Window.

Apparently not only was DX9 removed in 2017, which at that time killed exclusive fullscreen, Unity was wonderful and brought it back (I have no idea when).

This past knowledge of this problem made me (stupidly) assume the option wasn't there, since DX9 removed it.

The option is there. And all problems solved by switching from "Fullscreen Window" to "Exclusive Fullscreen" (true fullscreen).