Saftala
Go to the larger Judaica websites (eichlers, nehora…) and see what they have under the Bar/Bat mitzvah gift tab. Can’t go wrong with an inspiring book in my opinion unless the kid is really frum and doesn’t need it in that case ask the kid what they want, if that’s not possible maybe ask the parents of the child, if that’s also not possible just get a gift card to either a Judaica, toy store or clothing store (that the kid would appreciate!).