you have to search first the bandit's camp at night and after that during the night press the option sneak inside until you have a dialogue with the boss of the bandits jester >:|
You can't meet them at this point. Jester is not the bandit boss, I meant Scar and Tank, who Jester mentions in your dialogue with him. The boss fight with them is not implemented yet, but Hyao has already posted their concept arts on his Patreon if you wanna check it out
