Changing Resolution

Hey there, I have an ultra-wide monitor (3440x1440p @ 144hz) and I'm trying to get my Sea of Thieves (Steam Version) to run windowed at 2560*1440p. However I'm struggling to get it to work. I only need this as I want to stream SoT in 16:9, while having streaming tools such as Chat, OBS, etc. open on the empty space. Any suggestions on what to do? I managed to get it to work on the Microsoft Store version just by using the cursor to resize the window, but not happening on the steam version.