Whatever Persona 5R is, we are on the cusp of an official announcement, it sounds like.
Persona 5R is allegedly the expanded re-release of Persona 5, in the vein of Persona 3 FES and Persona 4 Golden. Judging by rumors surrounding the inclusion of Joker as DLC in Super Smash Bros. Ultimate, it is also rumoured to be coming to the Nintendo Switch. However, rumors are all these have been thus far. We haven’t had any official word or indication from either Nintendo or Atlus yet.
That said, whatever Persona 5R is may soon be announced officially anyway. According to Persona Central, the domain for Persona 5R, registered by Atlus a while ago has been updated. Citing examples such as Persona Q2 and Catherine Full Body, Persona Central points out that Atlus usually updates domains on the eve of official announcements, and that we may therefore expect a Persona 5R announcement soon enough.
Will it be during the concert Atlus has already announced for April? Or maybe in a January Nintendo Direct? Maybe it will be neither, and Atlus will just randomly drop the announcement one day? Who knows? Hopefully it is announced soon either way.