@Ivyy both my younger brother and I suffered badly from acne throughout teenhood (and as a young adult myself).
I tried all sorts as a teen - Erythromicin, lymecycline, spironolactone, topicals (clindamycin, differin, duac)... nothing worked for me until roaccutane. At that point I was in my early 20s so out of puberty and ready to try roaccutane.
The reason I point out my age is because roaccutane was super effective but came with lots of side effects which were easier for me to manage as a young adult. You HAVE to be on birth control, even if you are not sexually active (that was the rule at the time), your skin seriously dries up and you are super sensitive to the sun, my skin definitely got worse before it got better. At that point in my life I was confident to not wear makeup and not feel judged by people clearly looking at my spots/scabby skin. It can also give you mood swings/is linked to low moods which as we know can peak during puberty
After my trial and error, when my brother hit 16 and also had no luck, my mum was keen to pop him on Roaccutane and it worked a treat for him.
I think if she can wait a few more years I would encourage her to given the strength of Roaccutane and it's side effects. There is a high chance that after she goes through the main puberty changes it could clear up. If she is struggling with her appearance, there's an app called 'we are luna' I highly recommend for her to look at, there's lots of stuff on there around body positivity and teen skincare but also she can read what other teens are asking about acne etc to medics to see she isn't alone in her acne journey.
I still live by Cetaphil (the cleanser my dermatologist put me onto whilst on Roaccutane) - it was the only product that gave me relief but also stopped me from breaking out further.
On the bright side, my acne has mainly stayed at bay and never come back in full force, so it was definitely a one and done solution!