Rerolling your account in Persona 5: The Phantom X (P5X) can be a strategic move to get the best possible characters and items from your first few pulls. To do this, you’ll need to log into the game using a guest account, which is automatically created for fresh installs or can be changed by clicking on the “User” button.
Play through the opening of P5X until you unlock the Contracts menu, where you can pull for new characters. This process takes around 30-45 minutes, including skipping cutscenes. Claim your pre-registration rewards and bonus resources from your in-game mailbox, and check the events section for additional freebies.
To make progress in the main story and earn Meta Jewels to pull from the limited banner, continue battling Shadows and claiming any rewards that appear along the way. Once you’ve made your first pulls, you can either bind your account permanently if you’re satisfied with the results or delete everything to start over.
When rerolling, prioritize getting a targeted character, such as Joker, who is an excellent Curse DPS unit. If you manage to pull Panther, even by chance during your initial pulls, you can upgrade her to Awareness level 1. Any other 5-star Phantom Thief will also make a great addition to your roster.
If you get lucky and snag a 5-star from your first set of pulls, consider binding that account instead of trying again for the perfect roll unless you’re specifically aiming for a certain party composition.
Source: https://www.ign.com/wikis/persona-5-the-phantom-x/Reroll_Guide_-_How_to_Reroll_and_Best_Starting_Picks