Is there a grandfather clause for the new tobacco law

No

Explanation:

The United States recently (December 2019) passed a new law that raised the legal age for smoking from 18 to 21. This law is meant to curb the youth epidemic of smokers that currently exists in the country. The new tobacco law does not include a "grandfather clause." This means that the law does not exclude those people who are between the ages of 18 to 21 (who turned 18 with the old law and therefore, might already smoke, but who will be unable to do so under the new law).

No there is no grandfather clause law for new tobacco.

Explanation:

This means that people between the ages 18 to 21 who have been buying tobacco legally under the current constitution will not be able to buy tobacco under the new law until they turn 21 and above.