Thank you this did the trick for me!
For those with ultrawide screens who would like to play 'pillarboxed' 16:9 and have AMD cards:
1. Set windows resultion to 1920 x 1080 (this might be optional not sure)
2. In AMD control panel, enable GPU scaling
3. In AMD control panel, pick scaling mode: center
4. In outer worlds, select fullscreen and 1920 x 1080