Will BISSA Shoe cabinet with 3 compartments, white, 19 1/4x11x53 1/8 " fit in a Citroen C5 Aircross 2021?

The C5 Aircross gives you a wide, square loading mouth: 41″ across and 30¾″ tall, with a floor that is actually wider than the opening at 41¾″ between the arches. Seats up you get 38¼″ of length; folding them stretches that to 67¾″, a gain of 29½″. The catch is the sill, which sits 29⅛″ off the ground, though the floor drops only 1⅝″ behind it, so boxes slide in level rather than falling in. Wide flat packs do well here; very long ones run out of floor before they run out of mouth. Lift heavy boxes to sill height first, rest them, then push.

BISSA ships as a single flat box, 54¼″ × 16¾″ × 3″, and it weighs 45 lb 15 oz. At 3″ thick it slides into gaps a built cabinet never would, so the thickness is not your problem. The length is. At 54¼″ you need a trunk that measures long enough on the floor, or one rear seat folded so the box can run forward between the seats. Most hatchbacks take it with the seats down, and any wagon or SUV swallows it flat. Lift it on edge with two hands, and rest it on a long edge rather than a corner, because 45 lb 15 oz of flat pack lands hard and the corners split first.