Winning high-level competitions for anything, including music, does help to establish a “spike”, which can make a highly competitive school want you. It also speaks to a good student’s ability to manage their academic work competently while also spending many hours a week on a demanding extracurricular activity. So yes, it does help. It also helps for that achievement to be in something that the school seeks. They want students who are going to contribute to campus life. But the main reason for you to be doing music is if you’re still enjoying it - otherwise, it’s not worth the many hours of practicing required.
You cannot go back and fix freshman year, and I wouldn’t bother trying to. Everyone knows that some students had a really tough time adjusting to on-line schooling. You did very well in sophomore year! Only one B, and that in an honors chem class? That’s very good! The best thing that you can do is move forward, work as hard as you can in junior year, in the most academically challenging classes you can take, and get good grades this year, to cement your upward trend.
Is there any way that you can do any ensemble playing? Accompanist for the school musical? Play in trios, or other small ensembles? Keyboards for jazz ensemble? The reason that I say this is that schools don’t need a concert pianist, but they do need pianists for musicals, dance, and ensembles. This addition to your repertoire would make you a more attractive candidate, but if it’s not something that interests you, of course you shouldn’t do it. You don’t have to win competitions in ensemble playing. It just tells the school that you might be their go-to keyboardist for performance ensembles, which might vault you ahead of someone with similar academics to yours, but no campus life enriching talent.
If there is a prestigious conservatory with a pre-college program near you, consider participating in that. Top schools do seem to like the graduates of these programs, especially those from big name conservatories.
A stellar standardized test score would help in your situation, since it shows that 9th grade was most definitely a pandemic-related aberration for you, and I believe that it’s also considered as a contributing factor in the Presidential Scholar Young Arts competition. So try to prep for SAT or ACT, shoot for a high score in that. It’s an opportunity for you - you don’t want to just go test optional, unless you’re applying only in-state in CA.
Forget freshman year. The world is open again. Concentrate on your schoolwork and the extracurriculars that you love - if it’s your music, great. Just look forward. Continue along the path that you’re on right now, and it’s all going to work out well for you.