How do I get my iPhone 11 to rotate to landscape mode?
Orientation lock is off ant its a base model iPhone 11.
[Re-Titled by Moderator]
Then simply turning it should work if the app you are using supports landscape mode; not all do, and the Home Screen will not change to be in landscape mode.
The easiest app to check with is Camera.
Rotate the screen on your iPhone or iPod touch - Apple Support