Airlines have no interest in that sort of thing, most of them are close to bankruptcy and just trying to survive. Also, Airline training centers use only simulators, almost never real airplanes.
There are college-level flying clubs which do aerobatic competitions, I assume all of the aviation universities have them and probably some other universities too. There are also local clubs, but I don't think there are any prizes unless you make it to the national professional level. You would have to own, rent, or borrow an airplane.
This only applies to aerobatics, there no competitions or prizes for just flying a normal airplane in a normal manner.
Since any decent airline has thousands of applicants for each pilot job opening, they don't really feel the need to encourage aviation in young people. You might look at the civilil air patrol...kind of like boy scouts for pilots.