should be fairly easy, when you look at the pattern, to modify it to fit a different sized head.

UPDATE:
So as it turns out, I’ve learned that I crochet on the looser side. I would suggest using a bigger hook or bigger yarn (or both) to make this pattern workable for anyone who crochets tight or more in the middle (neither loose nor tight) side…I’m sorry for any problems this has caused anyone in trying to make this pattern work.