The GDPR is a law the EU passed requiring businesses, even foreign businesses, to protect the privacy of EU citizens.
Now of course, the EU's jurisdiction is not global, but the EU does have treaties with other countries they may permit it to enforce the GDPR in those countries or requires those countries to enforce it on the EU's behalf. For example, this answer implies the U.S. is one of those countries.
In which jurisdictions outside the EU can the GDPR be enforced?
Note that I am assuming that the whoever is violating the GDPR does not live nor has any assets in the EU that the EU could seize.