She doesn't, she's "defective" (she also has no legs in there actually, the box is part of her) - lore wise she was meant to be a toy factory's experiment on building one of their regular toys but human sized and with sentience (their regular toys are just normal toys), but the machine bugged out when upsizing the design and accidentally made her body extra-large too. If you wind up the crank on her box her head pops out instead to accommodate for this