Here is the full list of all 53 Persona 5 Royal achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Passed time at the fishing pond.
Attended the jazz club.
Completed the casino Palace.
Scored the highest on your exams.
Maxed out all social stats.
Completed the spaceport Palace.
Scored a prize in the crane game.
Completed the pyramid Palace.
Completely changed the cognition of Mementos.
Customized a gun.
Used Incense on a Persona in Lockdown.
Performed a Gallows execution.
Completed the bank Palace.
Maxed out one of your Confidants.
Performed an execution during a Fusion Alarm.
Performed a Showtime attack.
Visited a temple.
Entered a special relationship.
Couldn't take the heat in the bathhouse.
Scored a hit at the batting cages.
Cleaned up in Leblanc.
Played a game of billiards.
Played a game of darts.
Sold old clothing at Furugi no Neuchi.
Completed the museum Palace.
Encountered a deviation in Mementos.
Traded in flowers while in Mementos.
Traded in stamps while in Mementos.
Obtained a Skill Accessory from a Palace ruler.
Performed an Electric Chair execution.
Performed a Group Guillotine execution.
Went to a hangout spot with someone.
Obtained a Treasure Demon.
Worked a part-time job.
Triggered a Technical.
Completed a Mementos request.
Won the lottery.
Established your own squad of thieves.
Completed the castle Palace.
Defeated enemies via Disaster Shadow explosion.
Used the grappling hook.
Performed a Guillotine execution.
Performed a Baton Pass.
Obtained a Persona through negotiation.
Obtained Arsène.
Unlocked all achievements.
Completed the cruise ship Palace.
Completed Mementos.
Completed every Palace.
Watched the ending.
Evolved a party member's Persona.
Conquered the Reaper.
Ordered from the special menu at the maid café.