My observation is a little dated, but may still be helpful. When ShawSon was in HS, there were a group of girls he called the OCD girls. They showed up early every morning to go over their homework with the teacher to make sure they corrected any errors before handing the assignment in. They participated in many activities. Played on teams. Every hair was carefully in place at 6:30 AM. Overly conscientious. He thought the OCD girls thought they needed to be perfect at everything.
I don’t know if this fits your daughter, @L_Abbott, but if it does, it may be worth saying that no one knows exactly what elite schools are looking for, but it seems pretty clear as @HPuck35 says, that it is better to do one thing exceptionally well than many things at a surface level. That was guidance I gave to my kids and things worked out well. ShawSon followed my advice and ended up getting into and attending elite schools. ShawD also concentrated her effort on a few activities that she loved, but explicitly chose not to apply to elite schools (she decided to apply only in Canada).
I think that is advice that will help her performance and her high school experience (as @momofboiler1 suggested).