Girls who are 21 years old are in the prime of their youth. Even if they are bare-faced, they are still envied. They are particularly concerned about their birthdays at this time. After all, they will not be so young in a few years. So you must give a good gift to your senior sister on her birthday as a blessing. As for birthday gifts, I can also give you some suggestions:
1. Girls who are 21 years old are very pure and like simple things. You can give her a crystal pendant, which is a gift suitable for her age. The senior sister will also like it very much.
2. You can also give her a crystal music box. The beautiful crystal plus the beautiful music, I believe no girl can refuse such a birthday gift.