Just now catching up with story from seeing all these memes and I genuinely thought they needed these ears to beat Dottore

That's cause by equiping those animal ears they can roleplay as characters from a fairy tale, and then be immune to the rules of Teyvat. That way Dottore wont be able to read their threads of fate, so they can jump at him by surprise, throwing fictional apples for further emotional damage

Source: >! my dad works at Hoyo /cyno !<