What extracurricular activities would be best for tier 1 universities? Would certificates from online courses count as extracurricular activities? I do ballet, folklore, English (my native language is Spanish), robotics and science events. I can't do many independent things since I'm only 13 (ninth grade).
If by Tier 1 you mean schools like Harvard, Yale, etc., the thing you should focus on is developing out a passion or an area of interest that you care deeply about and can put a lot of time into. There is no magic bullet for those schools, and no "perfect" profile I can point you to. The area you develop can be related or not related to what you want to study, and it could look like a combination of the things that you're currently pursuing (even if they're very different). And as you develop that out, you should try to maintain a few activities over your full high school career so you can gain responsibilities in them and eventually leadership experience of some kind. That's what is most effective at getting these schools' attention.
To keep this community safe and supportive:
No worries! It's good to have multiple answers, even when they say the same thing. Helps confirm that the answer in general is right!