^^^ Exactly. And if USC is clearly your top choice, they do not mind hearing it. In fact, they want you to tell them so. You just need to have well-founded and properly researched reasoning to support your declaratory statement that USC is #1 in your eyes and that you will definitely enroll if admitted.
But let’s also be fair… only say so if true. It was true in the case of both of my daughters, so they said so… and did finally enroll after gaining admission. If you are a stellar applicant & a good fit for USC but emotionally committed to another school, I do not suggest saying so to USC just to increase your # of admissions. Let those who truly dream of attending USC have a better shot at doing so…