Hair Growth Remedies

Just curious. If you are a teenager, then is there a set “time” for your voice to mature.
And is it possible to extend your range still in the higher octaves? I want to be able to sing a top top E comfortably. I have a top top C at the moment.

I’ve heard that rosemary oil promotes hair growth and I would like to try it. Any other tips to promote hair growth would be very helpful.