If you take comissions as an artist and you're under 18 does it restrict you from getting an art scholarship?

I suppose it depends on the guidelines of the scholarship that you are applying for, but in most cases the answer is no.

In highschool I was commissioned for tons of work-- had my stuff in galleries and museums-- then went to school and got multiple scholarships, from the local, state and university level. There was never a problem, in fact, many impressed by the art resume I had made. No one ever asked about commissioned work, and I don't think they really cared. I am about to graduate from art school so this was just past few years. Good Luck!