Your cousin is only 9 years old, you can choose a gift according to the child's personality. Generally, children under 10 years old like toys, so it is recommended that you buy educational toys, such as jigsaw puzzles, Rubik's cubes, building blocks, etc., which can not only stimulate children's brains, but also increase their patience in doing things.
You can also choose a gift according to your cousin's preferences. This depends on your understanding of your brother. Giving your cousin a gift he likes is the best birthday gift. Anyway, just look at your cousin's preferences, and then choose what he likes.
Or you can buy him a good book, clothes, shoes, hats and other daily necessities, so that he feels that you care about him. You can also give creative gifts, such as life-like dolls, sunshine jars, shy bears, music boxes customized with photos, and name accessories!