I bought this from Ebay and it fits perfectly. It fastens by velcro to the sides of the boot area and by elastic to the rear seat headrests. It also provides a bumper cover to stop scratching the top edge. I dont have pets. It was about £20
Heavy Duty Car Boot Pet Cover Protector Liner For Jaguar E-Pace E Pace 2017 On
Only drawback is that you cannot lower the rear seats individually, only all of them together without removing it.