This statement is groundless. People's faces and jaws are born, and they can't be changed through acquired training except plastic surgery.

On the other hand, in boxing, the chin is most likely to produce KO effect. In actual combat, protecting the chin is the foundation of a boxer and will not be easily hit. Strong neck and shoulder muscles can alleviate the strong impact on the head to a certain extent, so well-trained boxers generally have a strong shoulder and neck. If you see a person's neck is strong, the trapezius muscles on his shoulders are raised high, his upper body is strong, and his legs and feet are symmetrical and flexible, then he is excellent.