When playing in "New Editor Window" mode, entering the r.setres command does not change the screen size. This worked in UE4.27, but no longer works in UE5.0.
Not affect command and keep window screen size.
Affect command and change window size to 1920x1080.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-159084 in the post.