Xbox Series X on Wide Monitor?

I have connected my Xbox Series X to my LG 34 "ultrawide monitor and now the picture is stretched a little and filled over the whole monitor. I would like to know if I can somehow set the picture to 16: 9 so that I have edges on the sides. I don't mind that, the main thing is that it's not so stretched.

You should be able to find this in the settings, where there are also the FPS settings and the resolution settings.

Otherwise I would recommend that you maybe see whether this also works via the monitor yourself.