Sorry for the inconvenience, realme UI 3.0 and above versions one-handed mode can only be used in full-screen gestures. Please set the phone navigation method to full-screen gestures before using it.
Setting path:
realme UI 7.0: Settings > System & update > System navigation > Gestures
realme UI 3.0 & 4.0 & 5.0 & 6.0: Settings > System/Additional settings > System navigation > Gestures
Related articles: