In order to pickpocket in Assassin’s Creed Mirage, you have to play a Quick Time Event. If you would rather have pickpocketing set to automatic so that you don’t have to play through this mini-game over and over again, then you can check out this guide at Seeking Tech.
1. For the first step, you need to open up the Options menu in the game.
2. From there, make your way to the Gameplay tab.
If you are playing Mirage with a PlayStation controller, then you can change tabs by pressing the L1 and R1 buttons. On an Xbox pad, you need to use the LB and RB buttons instead.
3. Once you get to the Gameplay tab, move the menu cursor down to the Guaranteed Pickpocket option. It should show the following description:
Enable or disable autocompleting the Pickpocketing Quick Time Event. Please note that by enabling this option, you are not playing the game as intended to be experienced. This will also override Pickpocket settings from the selected Difficulty option.
4. Make sure that the Guaranteed Pickpocket option is set to On.
5. Exit the options menu and then return to playing the game.
Pickpocketing should now automatically be completely successful when you attempt it.