You can choose gifts according to the characteristics of boys. Generally, boys are not too picky about what gifts you give them.
Your brother is under 12 years old. I suggest you buy toys with high IQ, such as puzzles, magic cubes, etc. I think these kinds of gifts are good choices for your brother.
You can also choose gifts according to your brother's preferences and habits. Giving your brother gifts that he needs and gifts that he likes is the most important thing. The range of such gifts is relatively wide, and it depends on your understanding of your brother.
See what your brother likes, and you can cater to his preferences. Or buy him a book, clothes, etc., so that he feels that you care about him and value him.
In addition, there is no need to make a child's birthday too grand, and there is no need to let the child develop a mentality of comparison and vanity.