What is your state flagship? Why are you interested in a T20?
Even people with hooks- legacy, recruited athlete, under recruited minority, first gen to attend college- have very small chance of being admitted.
Has your current high school sent any recent alum to t20? Have the public schools? If not, I doubt which high school you attend will matter for t20 admissions.
Some small private schools just are what they are as far as ECs. Maybe a staff or faculty or alum could help you start a language club or new EC? But, if not, you’re stuck with sports or drama.
But, if new ECs are more important than culture , environment, support, it could be worthwhile to transfer.