Children generally like cute things. Your sister is only in junior high school this year, so she should still like things that little girls like. So it's ok to give her something cute. For example, some decorations, cute and unique. Here are some suggestions for you, I hope it can help you.
1. Children will like stuffed toys, especially little girls. Basically, every little girl will hug stuffed toys to sleep at night. Recently, a luminous pillow has been released. It is very beautiful to hug at night. When watching TV, it can also illuminate when you get up to go to the bathroom at night. It is very popular among little girls. I believe your sister will like it.
2. Real dolls are very popular among young people. You can make a real doll with your sister's head. It is a very novel and unique little idea, but it can also show personality.
3. As a girl, music boxes and crystal jewelry are more popular. Isn't it a wish for every girl to get a beautiful music box when she was a child? I believe your sister is no exception. Why not fulfill her little princess dream?