When it comes to the various dungeons and real-world locations that you visit in Persona 5 Royal, there are different requirements for unlocking each of them. For most dungeons, they are going to be story and calendar-based, so just moving along with the plot will unlock a new one. The main exception is Mementos, the mostly optional dungeon in the game. Mementos will reveal new levels and requests there for you to complete also as you do the story, but it is up to you to unlock them. How you go about this is by making sure to go through every single level of the dungeon until you reach the new ones. These usually come with checkpoints for easy access to there from then on. For real-world locations, many of these are tied to the story, but there are some optional ones that you can only unlock through certain means. For instance, there is the fishing area and certain date spots that you can visit with your Confidants. To access these, you will need to continue leveling up your rank with the various Confidants in the game to access these locations. Finally, there are some locations in Tokyo and also some dungeons in the Metaverse that are unlocked via the third semester that is exclusive to Persona 5 Royal. Once you beat the main game from the original Persona 5, you will be able to access these locations.