I don’t know you or your section or your band, so the advice I give is biased based on my own experiences, but at my school, being the best player does not mean you are the most fit to be section leader. It certainly helps, but it’s not a quid pro quo thing.
It sounds already like you’re not extremely confident about it and I don’t think that would work out well for you. If there are other, older people in your section, you might want to let one of them have section leader the next year because marching band isn’t just about talent, it’s also about experience. And I’m guessing some of the other people in your section have been playing or at least marching longer than you, so don’t be afraid to just wait.
If you’re a great player and your section is small, it’s good odds you’ll get section leader your senior or possibly even your junior year. So my advice is wait another year. Stick to just playing well for right now.