Always read what you are signing. Always. Read the fine print and question anything that is off. If you signed it, it’s yours. But you should be able to at least cancel the warranty. They gap insurance may be a requirement from the lender

CarFax mileage isn’t always right. Especially if the last odometer reading was at an emissions testing place. Those people don’t pay attention. I bought a 2014 Prius 2 years ago with 6.6k miles. CarFax showed the car was last recorded with 66k miles at the emissions test facility Because they made an error.( I had copies of all the service records proving the car only had 6.6k on it)