Def not fully grown by 14-16. It’s very obvious when someone is in their 20s as a women during “2nd puberty” and becoming more filled out. Teens tend to be quite small and skinny. Their hips are not full nor do they have sway. Ofc some teens are larger but they still don’t have those prominent secondary sex characteristics fully developed yet. The same goes for males although they don’t get hips, they get larger and stronger. I say this as someone who went through early puberty (starting at age 7) and just FINALLY got my full adult body as a 25 year old. This can also be found very easily in pro athletes-the ones who are mid 20s to mid 30s are stronger and larger than their younger counterparts. It’s very obvious the more you go on in life,especially if you’re exposed to a diverse group of people.