An actress must struggle between real life and on screen to be a normal high school student when she helps a ugly duckling female classmate into being popular with rags and riches.

I can see two angles here:
Scheme 1: The high school actress performs a rag to riches makeover on an ugly duckling classmate in hopes of getting the attention off her for a more normal school experience, but things hit the fan when…
OR
Scheme 2: What if your protag was a former child actress desperate to make a comeback via this ugly duckling makeover publicity stunt, but things hit the fan when…

Take care.