Since I cannot reach that resolution with the in-game options how do I reach it with command line arguments?

https://steamcommunity.com/app/237850/discussions/0/2132869574264265185/

This command line argument allow me to fill the whole screen, but how do I make it borderless?

-screen-width 3440 -screen-height 1440

This doesn't seem to do it :
-window-mode exclusive


Edit:

It seems I don't need to be in windowed mode, full screen is fine with just:
-screen-width 3440 -screen-height 1440