My advice is to seek out every opportunity to gain leadership experience as possible.
Civil Air Patrol/Boy Scouts/JROTC are all great extracurricular activities to get involved with and each provides many leadership opportunities. Does your school have a
Link Crew program? If so apply to be a Link Leader. If your school doesn't participate in the program, speak to your Principal and tell him/her you would like to found a chapter at your school. Our area was not sending students to Girls State due to Covid when my DD inquired, but I know the SAs view Boys/Girls State very positively. It's not just about grades and sports. USAFA is looking for a Congressional nomination, a good CFA score, leadership, test scores, character, academic rigor, grades, and sports.
If you are a soccer player...you are a runner (unless you are the goalkeeper). Have you considered going out for the track team as well? It will give you another opportunity to captain a team, maintain your fitness, and earn additional varsity letters. According to the
USAFA Class of 2025 Student Profile, 25% of accepted students participated in track (the most popular sport). Plus if you are accepted to USAFA you will do a lot of running at altitude. Fitness is huge!
You will also need letters of recommendation from your high school counselor, a junior/senior math teacher, a junior/senior English teacher, another teacher (preferably a junior/senior science teacher), and your coach. Your senior year teachers will barely know you when they have to write your letters, so I would focus your attention on your junior year teachers. You should give them every opportunity to tell USAFA how incredible you are by being incredible! Make sure you are asking smart questions in class and leading discussions that will benefit the other students. Always offer to help struggling learners or go out of your way to welcome students who have just moved to your district and don't know anyone. Go to teacher help sessions even if you feel like you have a good handle on the material... the more they know you and the more they know you care, the more they will be willing to go to bat for you. All of these things are important.
Best of luck to you.