How can you leave a room with two legs and return with six legs

“Bring a dog back with you”

While a dog has four legs, it doesn't fit the context of a room and a chair, which is a common object people use.

“Wear pants with extra legs”

Pants do not actually have legs; they cover the legs of the person, and this interpretation strays from the intended object of a chair.

“Use a walking stick”

A walking stick is a single object with one leg, not six, and does not satisfy the riddle's requirement of returning with six legs.