I do not think that you should worry about it.
Take the classes that make sense for you. Keep ahead in your classes and strive for good grades. In terms of other activities, do what makes sense for you and do it well. Understand that Harvard is a reach for everyone (not counting Nobel Prize winners and the children of the leaders of friendly countries). Make sure that you apply to safeties, look for a good fit in universities, pay attention to your budget, treat people fairly, and find time to have some fun.
I never applied to Harvard. However, this approach got me accepted to MIT for my bachelor’s and Stanford for my master’s. This approach has also worked for other family members, but what I did and what my wife did and what my daughters did and are doing were all different things.
And here is a pointer to the blog that I think that you should read. It is on the MIT admissions web site, but at least IMHO the same approach applies to Harvard, Stanford, and other top ranked schools.