Yes, royals can get tattoos. While there aren't explicit rules against it, it's often seen as an unspoken guideline against body modification.
Even with this unspoken rule, several royals throughout history and in modern times have chosen to get inked. While royal protocol dictates much of their public appearance and behavior, the decision to get a tattoo is ultimately a personal one. The perceived appropriateness often depends on cultural context and the specific royal family's traditions.
Therefore, while not explicitly forbidden, tattoos are often considered unconventional for royals due to the emphasis on tradition and decorum. Despite this, many royals do have tattoos.