You’re way, way ahead of yourself.
When I was in 9th grade, I didn’t know what the Ivy League was. I eventually got into one.
Trying to prepare for one of those schools won’t get you there.
Formulas don’t work. Resume-building doesn’t work. Those who get in do something or some things that are unusual, have a specialty niche, and most importantly, that they can’t be stopped from doing.
Have some fun in high school. If you naturally do the right things, you might get into a top school. If you don’t, it won’t be the end of you, anyway.