Change resolution in Fortnite (PC) without opening the game?

I changed the resolution of Fortnite to 765p. The problem is that the monitor can now not give the picture again. Can I reset the resolution without opening the program?

If you have an Nvidia GPU, you can change that in the GeForce Experience. To do this, simply click on the game and to the right of "Optimize" you can change the resolution.

That can be done somewhere in the game files

Should be in the settings

Heyho the resolution can be adjusted in the gamefiles how that works would be complicated to explain now that's why I picked out a tutorial for you.