I got 3bs in my first semester of freshman year in high school. After that, I got all As in the hardest possible courses. I ended with a 3.9 GPA. I also have a 1560 and got all 4s and 5s on 9 APs. I have no excuse for those 3 Bs, as I just wasn’t adapted to high school. Will those 3 Bs affect my chance in being admitted to top schools such as HYPSM?
No. Or yes. Or maybe. It is what it is and you cannot change the past.
Note that every single HYPSM school routinely rejects applicants with perfect stats while admitting some with lower stats
All applications are reviewed holistically; grades are just one part of the package.
Understand that they won’t automatically sink your application, but it’s ridiculously difficult to get into those schools. It may not be that B’s in your transcript will sink your pap, as much as someone else’s app will rise to the top.
Every part of your application matters. But in context. Three single letter grades, three years ago, among 40-50 semester grades, in one part (GPA) of you application, is a very small component.
I can’t say it is meaningless. But a single typo in an essay would probably be of an equivalent impact. Or greater.
As noted, it’s in the past, you can’t change history or do anything to address it, so the question and any answers here don’t really mean much, IMHO.