Adding that torso:legs ratio isn't dependent on age or height. It varies between people based on genetics, but stays pretty consistent.
As an example. I have unusually long legs, they're over 50% of my total height (above average)...but my total height is only 5'1" or 155cm. However, I've always had these proportions, and my sister, who is around 5'5" or 5'6" and brother, about 6' both share these proportions. My sister's daughter also inherited long legs, even though she's only seven years old and below five feet tall. So I can confirm, unless you're looking at a very young child, your legs:torso ratio won't change with age.
Head: body ratio tends to have the head a bit larger on smaller people, but there's not a huge difference between say, an adult of 5'1" like me, and a thirteen year old boy who is 5'1" whose adult height will be 6'. So generally when drawing teenagers, draw them proportional to their current height rather than worrying too much about whether they're still growing or not. Especially since women and AFAB people often hit their adult height at about fifteen, and men or AMAB people around sixteen or seventeen, so with most stories about high-schoolers, everyone will be roughly fully grown.
The differences with teenagers tend to be more in things like the width of the shoulders and pelvis. Younger teenage boys have the more "1.5x head width" shoulder measurements more similar to women, while an adult man could have as much as "2x head width shoulders" if he's particularly broad shouldered. This doesn't apply to everyone though... not every man is proportioned like Chris Evans.
There aren't hard and fast guidelines because everyone's different. We all mature at different rates, and a person's genes and upbringing can have a big impact on how they develop.