How Does Being A Transient Student Work?

I am currently a sophomore at my high school and I want to take some pretty hard classes senior year that my school doesn't offer, these being AP Physics C Mechanics and AP Physics C Electricity and Magnetism. Alongside these courses I will most likely be taking Multivariable Calculus, AP Lit, and AP Mandarin. I was wondering if I could apply to become a transient student at any top tier colleges (MIT, UChicago, etc) and how that would be possible. Any information helps some specific questions are:

-What do you need to become a transient student? (Coursework, Recommendations, etc)

-Can you become a transient student at one college before applying to the main ones you want?

-Do schools like MIT, UChicago, etc, often take in transient students?