I would ask him what he'd like to do for his 13th birthday. . . party, no party, spend it with friends, family, just the two of you, etc.

Sometimes my kids prefer a family outing/overnight stay, etc. to a party. A night in a motel with a pool is a wonderful treat for kids who never get to do that. Even if it isn't too far from home. Room service, etc. Once we gave our kids the money we would spend on the birthday and took them to shops where they enjoyed going. They loved it.

My mother was big on special occasions marked with something special. One of the first "growing up" things we got was a nice watch. . . usually for 8th grade graduation. A thing she did for the boys in the family was very nice key rings with their initials engraved, or a nice small pocket knife and have his initials engraved on it . . . signaling his maturing enough to treat it as a tool and not a toy.