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