Composition Supplements

Hi there, I’m very new to this site, so I apologize if this is in the wrong place. I’ve been composing music since I was seven but never have taken composition lessons (I’ve been playing piano for many years however). I love composing, and am considering writing my essay on it, but I’m worried that if I do submit a composition as a supplemental, it will do more harm than good. It’s hard for me to tell how advanced the piece I’m considering sending in is, since I’ve never entered it into a competition or anything like that. Could anyone give me any idea of how common composition supplements are, how advanced prestigious schools expect them to be, or anyone to talk to to evaluate my piece before I send it in?

Thanks so much!