GDPR applies to all data controllers anywhere on the earth, if you hold private data of EU citizens or residents and don't follow the GDPR then any EU country's

GDPR applies to all data controllers anywhere on the earth, if you hold private data of EU citizens or residents and don't follow the GDPR then any EU country's data protection authority can choose to prosecute. The only way to avoid the GDPR is to not hold personal identifying information on any EU citizens or EU residents.