If you're referring to the 21:9 "Ultra Widescreen" aspect ratio, that's what I have, but it's 34" (LG 34UC89G). Whether a specific game can support higher/wider resolutions is actually determined by each game. Not looking at the moment, but IIRC WOFF UE seemed to adjust the aspect ratio in-game to 21:9 format as expected.
Older games might be expected to behave otherwise; I still use some games originally written for 800x600 (4:3 aspect ratio) and they will often just center a 4:3 image on the screen by showing black "pillar boxes" at each side. Depending on the monitor and the software (and sometimes, GPU, to a lesser extent), there may be adjustments for whether the image is 'centered', 'cropped', 'stretched', etc. when it's not in the display's native format.