You could consider Stanford Online High School, but I do not know if I would recommend it.
If you would like to find out all the basics of the school, you can see their website. https://onlinehighschool.stanford.edu/about
The way the school is organized and how their students interact is highly unorthodox but surprisingly effective. Many people struggle to understand precisely how it works, so please read up on it before you continue or else the rest of what I have to say might be confusing.
It is a highly competitive, expensive, and reputable online high school. I remember last year they reported that 60% of their students who applied to UC Berkeley were admitted. Many students also get accepted to Columbia and other LAC’s in the Northeast every year. I also personally know a few girls who got accepted to Duke, Carnegie Mellon, Tufts, and College of William and Marry. I, myself, am going to UNC-Chapel Hill. I am definitely in the bottom half of the graduating class of 2018, but I went there for only one year. Generally speaking, they know how to prepare their students for elite universities.
Bear in mind though, it is not for everyone. It is probably the most expensive online school out there, and for good reason. Most of their instructors have PhD’s in the disciplines they teach and care deeply about the success of their students. Even most colleges do not have professors like that– people who have command over their discipline AND are passionate about teaching it. They also have dedicated and highly qualified advisors, counsellors, and other support staff. In fact, my HR instructor had a PhD in biology from Stanford! It is also quite a premium experience. Their website, student portal, tech support, and course resources are all very thoughtfully designed and aesthetic. Also, most of their students come from affluent backgrounds, so expect to be socially excluded for some live/in-person events, some of which are on the campus of Stanford University. About 1/3 to 1/2 of the student body is from California though, so Palo Alto is an easy trip for some of them.
Being a competitive school founded by one of the highest ranked universities in the world, it is no surprise that Stanford OHS brings with it an exceedingly stressful learning environment. They accept world-class swimmers, models (Yes, there was once a student who did fashion modelling in LA while going to OHS. She was accepted to Stanford University upon graduation.), tennis players, and fencers as students who manage to balance the intense academic workload with competitions and tournaments. Last year, they even had a page on their website that showcased the achievements of these students, so you could be reminded every day that there are students out there–your age and at your school–that are literally curing cancer or winning international-level olympiads. Many students also cram their schedules with AP or university-level courses, which the school offers plenty of. Said students can overshadow the rest of the student body and create a sense of endless self-inadequacy. Our 2018 senior class president explains more, here https://itspossiblelab.com/, on her blog. My point is, unlike at some other schools, it is impossible to become a “top” student here since even if you manage to become the best fifteen-year-old golf player in the world, you may find another student who has conducted published medical research with nobel laureates at an international university, or something like that. No one ever feels intellectually validated or secure– it’s miserable.
That being said, they offer plenty of AP/college-level courses, are highly respected, and can get you into a top 20 school as long as you put in the absurd amount of effort and resilience that it takes to survive here. 90% of the misery comes from the competitiveness and academic rigour, and the other 10% is from being online almost 24/7. I, personally, did not have a great time there, but your experience might be different.