I deliberately leave the most recent delivery box out for my cat to lounge in. Sometimes it’s a small studio flat, other times (like when my 3d printer arrived) it’s a whole palace. She likes them either way.

Mine likes them as well, but usually within 24 hours they're transformed into thousands of tiny cardboard pieces.

Chewy.com deliberately indicates that its boxes are for cats.

Also, their brown paper filler is loved by my cat. He doesn’t like Amazon packaging paper, but is all over Chewy paper. I wonder if they add a scent.