They certainly look like implants, given how thin she is.
Is it legal for a 16yo to get a boob job? I would think not.
There’s 13-year-olds out there getting cosmetic surgery. Age means nothing. An ethical plastic surgeon would never give a 16-year old girl breast implants, but ethics means little these days to many people, especially if there’s a screaming stage mother on the other end of the phone line.