In ninth and tenth grade, I was very involved in both STEM and music extracurriculars. I took AP Music Theory, Wind Ensemble during the school year (only because it was required to participate in marching band), and every music ensemble after school (jazz band, pit orchestra, marching band). I have a wide range of leadership positions in all of these groups- everything from soloist to first chair to section leader. Now as a sophomore going into junior year, I realized that I lost my love for music and want to focus on my STEM activities, since that is what I am passionate about. Will this look bad to Ivy League college admissions officers who will see my transcript and see that I have taken music courses my first two years of high school? Will it look bad that the majority of my extracurriculars will be STEM and I will have no variety? Will it look bad that I started all of my STEM extracurriculars as a sophomore in high school, rather than as a freshman? (I don’t know if this helps, but I am a female of Pacific Islander origin)
I do not think that any of us can be quite sure what will or what will not get you accepted to a highly ranked university.
I think that you need to do what you want to do, and do it well. Then make sure that you apply to at least a couple of good safety schools, and see what happens.
I think that students spend too much of their lives trying to figure out what selective universities are looking for. There are a lot of very good universities. I do not think that you should spend the next two years doing something that you do not want to do.