My cousin (F10) has been getting bullied and it caused her to become insecure. How can I help her?

Hello! Recently, I received a phone call from my aunt to let me know that my younger cousin was being bullied, and she wanted me to try and talk to my cousin. Many girls in my cousins class told her she is hairy and that her arms are like Chewbacca and called her other nasty names. My family is Indian, and we generally have a lot of body hair. Because of this, my cousin has now refused to wear shorts sleeves to school. I live in the east coast and we are currently experiencing a heatwave, and even in this temperature she won’t even wear a short sleeve at home. She won’t believe anyone in her immediate family when they tell her she’s beautiful the way she is. My cousin really looks up to me, so my aunt asked me idea try and help my cousin out. I have no life how to talk to her about this. I don’t want to give her “solutions” like shaving her arms or bleaching the hair because I worry that that might cause a bad mindset of “fixing” insecurities instead of embracing who she is. I want her to feel confident in herself and her looks. She refuses to talk to the teacher because some of these girls are her friends, and she doesn’t want to cause drama right before the school year ends. What do I say when I talk to her? For context she is in 4th grade. Any and all suggestions are appreciated!!!