@PurpleTitan Large scholarships are extremely hard to get anywhere, but UMich does have >200 large ones in LSA and CoE that are $5k-$10k for in-state and $10k-$20k for OOS. There are also ~50 full tuition to full ride. In addition, UMich would meet the need of OOS with family income below $90k. So it is possible that UMich may provide better FA than CMU to OP depending on his family financial situation. Would his HS let him proceed with OOS public college application is another story.
It seems OP is having a second thought on the ED school not because the FA is much lower than expected, he just thought he can simply back out if it is too expensive and did not even check the cost before application. It is true that one can always decline an ED offer if it is not affordable, but it is often not without consequence. He could have choose to apply other SCEA/REA school instead of applying to an ED school with unknown cost. He may have loose other opportunities as well depending on his high school policy on ED withdrawal.