Not every app takes advantage of the phone’s capability to orient itself in landscape mode. For example, the Home screen does not rotate. If you want to verify that landscape mode is working correctly, launch a web browser on your Robin, navigate to any website and rotate the phone to landscape.
Android phones have a setting you can check to confirm that landscape orientation is active. Check the quick actions drawer for the Auto-Rotate setting. That setting might also be found in the Settings app, on the Display screen.