A strong and large masseter (chewing muscle) can give a square appearance to the face. Often people of Asian descent will have strong masseters and a square jawline.

If you are looking for a more angular lower face a good approach is to treat the masseter with  BOTOX which reduces the size of the muscle which sits at the angle of the jaw.

The result is a thinning of the width of the jaw. The face moves from a square shape to a heart shape which tends to look more feminine. This treatment can also be very effective to stop teeth grinding.