Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Set the availability of full screen mode - all Microsoft Edge UI is hidden and only web content is visible. If you enable this policy or don't configure it, the user, apps, and extensions with appropriate permissions can enter full screen mode. If you disable this policy, users, apps, and extensions can't enter full screen mode. Opening Microsoft Edge in kiosk mode using the command line is unavailable when full screen mode is disabled.