I haven't used your model of Samsung but you should be able to pull down your notification shade from the top of your phone to show your toggles to which one should hopefully be Auto Rotate.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
@HaggisIan: If you swipe from the top of the screen to the bottom, then again to enlarge the Quick Panel, then Auto Rotate should be visible here. If you can't see it, look for a grey padlock symbol with 'Portrait' written below it, and tap on the padlock to enable Auto Rotate.