No mods, and no support in the game for 21:9. It is old DirectX v9 tech. Only 4:3, 5:4 and 16:9 are in the game. There was a fellow on SubSim a few months back attempting such a mod, but they have not posted in a while. Try an off-site search engine with "Site:subsim.com/radioroom "SearchTerm (s)" and see if you can find anything. I was not, but these search engines are all Google-clones anymore... I was running my game at 4k for a while, the dropped to 2k (my poor eyes cannot see the interface at 4K), but I am back to 1920x1080, since other than the smaller interface pieces, I cannot tell any difference. I do understand though, the desire for a 21:9 view...