yeah, i remember from my old drawing textbooks as a kid that typically shoulders are double the width of the length from chin to top of the head, it varies a little but not by that much
having said that, i can recall seeing a few people in my life who seemed to have inordinately large heads compared to the rest of their body, and my head, also, is actually quite large, like, my head is the size like someone who is almost a foot taller than me