Yes, good posture can help reduce a double chin. Improving your posture aligns the neck and spine properly, which can minimize the appearance of a double chin by preventing the skin under the chin from sagging and accumulating fat. Maintaining an upright posture with the head aligned over the shoulders helps to strengthen the muscles around the neck and jawline, contributing to a more defined appearance. Also, specific exercises to improve posture and strengthen neck muscles can further aid in reducing a double chin.