Giving gifts depends on the person. People with different personalities like different things. I don't know which type your girlfriend belongs to. You can carefully observe what your girlfriend needs. The best gift is to give her something she wants but doesn't have. You can ask her best friend for advice.
However, you can also try some things that girls generally like. For example, cosmetics, every girl needs them. Light makeup can make her beautiful face more attractive; high heels are also good. Girls in their 20s must have their own high heels. Whether they like it or not, they will have more and more opportunities to use them.
However, in my personal experience, the most lethal thing is roses. Every girl likes romance, haha. But if you have given it many times, you should consider something else. I hope my answer can help you.