Face Shapes vs. Hat Shapes
There is no "good or bad" shape to one's face. It is what it is! So select your crown accordingly.
Select a hat with a shape other than that of your jawline. Think of it like this: If your face is round and you have a round crown, you will look like a ball. If your face is oval and you have an oval crown, you will look like an egg. If your face is square and you have a square crown, you will look like a box. In nearly most cases, the crown of the hat should not be narrower than you cheekbones.
Brims usually don't get wider than the shoulders. If you're shorter, lean towards the narrow brims and the bigger you are, the bigger the hat you can get away with.
There are always exceptions to any rule and that is "the golden rule" which supercedes all the rules above, is to wear a hat you feel comfortable and confident in, in a style which suits the occasion. OWN IT!
What is the “correct” hat fit?
Whatever feels right to you. There is no “correct” hat size for you. A tighter-fitting hat stays on better when the wind blows. A looser-fitting hat is more comfortable. Some people like them high and tight, others lower and looser. It is entirely a matter of personal preference.