The state may do that without violating the Constitution. Indeed, the state could potentially outlaw the sale of tobacco altogether no matter the age of the buyer. There is no denial of a fundamental right here because there is no fundamental right to buy or use tobacco or alcohol, and thus such challenges would fail. Indeed, it would be easy (from a legal standpoint, if not political) to ban completely the sale of tobacco as a hazardous substance since studies have shown absolutely no health benefit to tobacco and have demonstrated significant health risks to the use of it.
The abortion decision of Roe v. Wade involves a very different subject, it has nothing to do with buying any product, and thus is not on point. You wouldn’t get far trying to argue there is a connection between the two. There is a fundamental liberty interest involved when deciding what kind of medical procedures a person will or will not have performed. That’s not what is at stake with the purchase and use of alcohol.

