Can you retake your SAT or ACT to get accepted into a better college as freshman if currently enrolled in another college?

Yes, you can retake the SAT or ACT while enrolled in another college to potentially improve your scores and apply to a better college as a transfer student, not as a freshman. You cannot typically use improved scores to *retroactively* change your freshman admission decision at your current college. You'd have to apply to your target college as a transfer student, usually after completing at least one year (sometimes a full academic year) at your current institution.