If I understand the American high school system correctly, 3.5 is not a particularly high bar, especially with grade inflation in recent decades. For context, most students admitted to Harvard or Yale have close to a 4.0 weighted GPA. It would be like randomly picking among students who scored >70% on some exam, instead of picking the top x%.
Furthermore, GPA is not very comparable between different high schools.
I'm assuming that's 3.5/4.0. At least where my kids are in school in Texas, that ceiling is now 5.0: if you take honors/AP classes, they're weighted a full point above the "ordinary" classes, so if you take all advanced courses and get all A's, your final GPA will be a 5.0.
Furthermore, GPA is not very comparable between different high schools.