Please note that this guide is for Nvidia Control panel users only. It is possible with amd gpus too though.

Step 1. Go ingame and check video settings and take note of the effective resolution
My default monitor resolution is 1920x1080 yours might be different and thats ok.
Next you should change the aspect ratio (move it right) until you see wide and ultra wide.
Take note of their effective resolution Wide is 1920x810 and ultrawide is 1920x540 yours might be different and thats fine.

Step 2. Make a custom resolution of the effective resolution you want in nvidia control panel, Example: Ultrawide was 1920x540 for me
to be able to use it, go in the customise screen again and tick the box until it shows up in resolutions under the pc heading.

Step 3. How to get rid of the black bars!
Go inside adjust desktop size and position, and select a scaling mode, the scaling mode that you want is Full-screen. if you are unable to select any scaling mode, go in manage 3D settings and turn Image Scaling off

If you have a different resolution than me (1920x1080), just take note of what the effective resolution of ultrawide that the game tells you is and then make a custom resolution based on those numbers.
Be warned though don't try to make crazy resolutions your monitor can't handle because you can get a black screen, do some research and you should be good. cya :)