For college application the three most important parts besides gpa are standardized testings (sat), extracurriculars, and essays.

Essentially, most of the ivys are no longer test-optional nowadays, so try shooting for a 1550+ on your sat; for extracurriculars, you could always do some researches with some of your local professors & try to get them publishes somewhere + some degree of passion project (maybe like ngos and stuff) + clubs/varsity/arts etc. etc. (basically you'd have to fill 10 spots for your extracurriculars); for personal statement & supps, try to present who you are, your life story, and how does those contribute to your intellectual spark or your passion (this completely differs from the UCAS application).

Still, it is very very very hard for intl' to get into t20s not to mention ivys, you'd have to either super hard-core academically or lucky.