Many colleges switched to a test-optional policy with the onset of COVID-19. However, some colleges (including MIT) have switched back to a test-required policy, so we’d recommend checking the requirements of each university on your college list. On the opposite end of the spectrum, a handful of colleges have committed to a test-blind policy (including the University of California system), meaning that they are removing test scores from consideration entirely.
In general, we do recommend preparing for either the SAT or ACT, even if many of your student’s target colleges are test-optional. If a student can achieve a score that falls near or above the median for typical students admitted to any given college, then submitting scores will only serve to benefit them. Your student can also always choose to submit their score to some schools and withhold them from others.