Need advice to as someone who wants to get into a t20 university that goes to a small school

Rankings are misleading. It’s like comparing an apple and a sweet potato and calling one “better.” And it’s the single worst criteria you can use to find a college. You need to find something that works for you. Selective doesn’t mean “better” or more “academically challenging.” Take a deep breath, get the best grades you can, keep yourself mentally balanced, and apply to a wide variety of schools you can afford.