I did attend top 10 universities (one for bachelor’s and one for master’s), so I am not sure how relevant my observations are. However, my experience is that most of the students there excelled at mediocre high schools. I did meet a small number of students from really top high schools. It seemed like they were given a little bit of slack. For example there was one student I knew at MIT who was 7th in their high school, but it was a really top high school. Being 7th in high school with no “hook” would not have gotten a student into MIT from an average high school, but did from a really top school.
I think that university admissions will have a pretty good idea of how tough the grading is in your high school. At least universities in your state will know how other students from your high school have done at their university. As such I expect that they will understand how a 3.5 from your school would compare with a 4.0 at a different high school.
I do think that “Georgia Tech, ucla, berkeley” would all be high reaches with a 3.5 even from a top high school.
But I also agree with other comments above that your guidance counselor would know better than I would.