When you are talking 3A vs 7A depth is a massive factor. Trinity Christian is one of the most talented teams in the state when you look at their top 22, and one of the best coached.
However, STA I believe would wear them down. The ability to rotate fresh bodies in and out of the game especially in the second half would be too much. I don't think STA would win by 30-40 points by any stretch. I think they'd win by 2-3 touchdowns though, pulling away late.