It sounds like your school is allowing kids to study under what we called "dual enrollment". Our high school kids could also do this, but transportation and time management during the school year is an issue. Just be careful with DE. Grades received from any of these DE courses factor into your final college GPA. Getting a B-/C+ or worse in these courses can derail your kid's aspirations for graduate or medical school. Personally I think there are more important things for a high school student to be working on, such as leadership roles at school, summer internships, volunteer and community service work, pursuing interests in music or sports, or part-time employment, etc. Inbox me if you want more of my thoughts on this.
Our high school let students take summer online high school classes for credit, but it needed approval from counselor and principal. Parents had to present information about the curriculum for review and approval, pay tuition and final grades were sent to our high school. My kid also completed the state-mandated Health and P/E classes this way. My kid also took a fine arts class for credit. We used The Keystone School for these classes, because my student could work at their own pace (bulk of the coursework completed during winter and spring breaks, online teachers available all year round). Keystone also offers AP classes. https://www.keystoneschoolonline.com/k-12/high-school.html
My kid needed a study hall every semester to slog through all the AP courses at high school while being able to compete year-round with their sport. We thought kid would commit to a Div III LAC, but ended up abandoning college athletics to take a gamble and applied to several Ivies during regular decision round when final SAT score came back in November senior year (jumped nearly 100 points to mid-1500's, we felt better SAT painted a more complete picture of my kid's high school academic career). Accepted to Williams, UPenn and Yale and (rejected from Harvard) during regular decision round. Our highly-rate public high school is pretty small, and the Ivy's usually only take one or two students from any graduating class (e.g. Harvard took 1, Yale took 1, USC took 1 who was a legacy, Stanford took 1 who was an athlete, MIT/Princeton/Cornell took 0 despite many qualified applicants).
(To be transparent, my kid was a first-gen, low income student who also worked most of high school, was 4-year varsity athlete who competed regionally as time and funds permitted, and was engaged in a multi-year social justice internship/fellowship since sophomore year.)