If you were holding out hope that your Persona 5 save data will somehow carry over to Persona 5: The Royal, we've got bad news for you: it won't. Given that The Royal is, seemingly, a much expanded adventure as well as a heavily tweaked one, the confirmation comes as little surprise, but it's still nice to know for sure.
Said confirmation comes from the latest issue of Famitsu magazine, which features an info blowout on the upcoming title. If you've spent hundreds of hours with Persona 5, crafting the perfect persona and mastering your social status, then this is perhaps a bit of a gut punch, but that's just how it goes.
There is a silver lining here though, at least to some degree. Atlus has said that having Persona 5 save data on your PS4 will unlock a "bonus" when starting Persona 5: The Royal. Hopefully it doesn't disappoint!