Something he can make/build. Lego,

Does he have any hobbies? does he like building things? Lego or models are great. How about sports and sports gear? Otherwise maybe an experience, concert tickets or theme park passes etc. Sometimes making memories is the bet type of gift.

Basketball court, football court, Blow up pool with water slide and water guns, books, paper air plane kit, science kits, guitar & music lessons, voucher to go wet & wild or something like that

Books are always good, and lego is a classic. What about model planes or similar?

Books. It could be a Roald Dahl collection for example or Geronimo Stilton or any other author he likes. A special kite, a scooter, some nice board game like “Game of Life”..

May something sporting or if he’s not into that an experience gift like a surfing lesson, a trip to a theme park (depending where you live) or an experience for what he’s interested in if it’s cars, music or something else. Good luck.