You are talking about some of the most competitive schools in the country. There is no way to guarantee admission. Take the most rigorous courses you can (especially in STEM), get as close to a 4.0 unweighted GPA, and be at the 98th percentile or higher for your standardized tests. And no, Bs in science are not going to cut it at the schools you mentioned.
IMO, you are better off not stressing during high school. Find the courses you enjoy, clubs that make you happy, and then find schools that are a good fit for you. There are hundreds and hundreds of schools in this country where you can be successful!
If you are planning med school (and it’s too early for that IMO), you want the most affordable undergrad experience possible, with the least amount of grade deflation. Some on your list most definitely don’t fit that bill.