I’d change it to 22 instead of 21, gives them a chance to get out of college alive.
Really, the people that want to drink are going to do it, regardless of how old they are. Same goes for smoking, drugs, driving without a license, possessing/using firearms, and various other behaviors people think can be controlled with a piece of paper signed by a politician. I have NEVER met a late-teen/20 year old that enjoyed drinking refuse to drink or attend a party because they were under 21. All of those laws only exist to make other people feel better about themselves, while having no effect whatsoever on the people/behavior they desire to control.