DISNEY VILLAINS HAVE SQUARE JAWS.

Whether in “Mulan”, “Tarzan” or even “Beauty and the Beast”, the villains in the story most of the time have a square and dominant jaw, unlike the main heroes who have a drawn, thinner face, nevertheless respecting the principles that make an aesthetic face, i.e. a jaw width equal to that of the forehead and a defined chin.
This is not due to chance, it is carefully thought out.

FOR WHAT ?

The square, pronounced and imposing jaw followed by a strong and well-defined chin are very virile attributes. They give a dominant look to the characters, so they look strong and unbeatable. This adds difficulty and challenge to the main characters who must defeat them.
Beyond that, the jaw completes its development after puberty. It represents the end of growth and the fact that a child's face has become an adult's face.
Since Disney cartoons are aimed at a very young population, the cartoonists represent the villains as adults with pronounced, even exaggerated secondary sexual characteristics, with a very manly face and a large jaw.
Conversely, heroes have finer facial features, a smaller and less pronounced jawline, which gives them a more childlike appearance, it creates a feeling of empathy. The watching child then identifies with the hero of the story.