The White House officially lists Trump at 6' 3" although that's been disputed./ Some reports claim that the White House doctor listed Trump at 6' 3"/239 lbs. so he could be listed at a 29.9 BMI. 30+ is considered obese. Barron Trump according to the USA Today article is 6' 3" at 13 years old.
I can sympathize with the kid. When I ended 7th grade I was 5' 2". When I ended 8th I was 5' 8". It isn't fun growing that fast and your brain doesn't coordinate that growth very well.