The PS5 version of Persona 5 Royal won't offer a free PS4 to PS5 upgrade for those who already own the game, it has been confirmed. A rather poorly translated page from the official Persona Channel FAQ says "we would appreciate it if you could purchase "Persona 5 The Royal" for PlayStation 5 when you play with PlayStation 5".
Just prior to that, it explains "there are no products for purchasers" of Persona 5 Royal on PS4. Essentially, there is no upgrade path; you'll need to buy the entire game over again. It means the latest edition has the same transfer process as the original Persona 5 to the enhanced Royal version, in that there simply isn't one. Although, Persona 5 Royal did package in a new semester, character, and other improvements.
Persona 5 Royal on PS5 will simply be a frame rate boost and a graphical refresh, although Atlus hasn't actually said what this new version contains. The DualSense controller will likely be supported in some way too when the PS5 version launches on 21st October 2022. Are you going to pay full price for Persona 5 Royal for the third time? Raise the funds in the comments below.