When you install an aftermarket part on your vehicle like a trailer hitch in this case, you are protected by the Magnuson–Moss Warranty Act. This act states, in part, that unless the installation and the part caused a problem then the warranty cannot be voided. I recommend looking it up online.
We do have the EcoHitch part # 306-X7377 as a confirmed fit for your 2018 Honda Clarity as well as the no-splice ZCI kit part # 119250KIT. We sell a TON of hitches for vehicles, some that are like... view full answer...