Research as a highschooler?

From your response to my comment, it sounds like you haven’t reached out to anyone yet. I usually advise students to initially begin with email outreach (find the professor’s email and send a message). The key is personalization — what can you include in the first two lines of the email that show you care about the professor’s research and have done your homework?

Separately, note that cold email outreach to professors is absolutely a numbers game. I’d guess your response rate will probably be something like 3% — that means you probably need to email 30 professors (with a personalized email) before you get a response. That may sound like a lot of work but it’s certainly worth it if you can get an opportunity. Separately, the process of getting to know a professor’s research and even just learning how to cold email is a pretty important skill (so the experience will pay dividends for you down the road).

Alternative avenues to research can include going through grad students (so doing the same cold outreach process but to grad students) or trying to get a referral from your high school (some high school science teachers have relationships with the local university science departments).

Hope this helps!

Prestigious universities really like seeing applicants participate in academic activities outside of school such as math or science competitions. Also, I'm not sure if you're interested in athletics, however Harvard really values athletes, as they know how to deal with and overcome adversity. So even if you aren't recruited to Harvard as an athlete, participating in some type of sport can really help your admissions chances!