If it fits
Cats like to sit anywhere they fit, and even if they don’t fit, they sit. While their flexibility can be a source of envy for us inferior humans, it seems as if this cat had trouble fitting in this box despite his flexibility, since he was hindered by his fur.
Either way, he didn’t let it stop him, and he managed to squeeze in as much fur as he could, and sit in the box, trying to implement self-isolation. We all know how hard it can be to find some peace and quiet in a crowded house, and the longer we’re locked in, the smaller the house seems to get. This cat was looking for a refuge, and he found one in the shape of a cardboard box.