When using hands-free calling, pick up and hold the phone close to your ear, then the hands-free calling will automatically switch to the receiver.
Path:
realme UI 7.0 & 6.0: Settings > Accessibility & convenience > Gesture & motions > Auto switch to receiver.
realme UI 5.0 & 4.0 & 3.0: Settings > System/Additional settings > Gesture & motions > Auto switch to receiver.
realme UI 2.0: Settings > Convenience tools > Gesture & motions > Auto switch to ear receiver.
realme UI R & T & S & Go & U Edition: Not supported
Note: VoIP (voice over Internet Protocol) is not applicable.