my iphone 13 is blue but the website i used to verify its authenticity says its red

What is the Model Number of the phone? Settings > General > About > Model Number

Which website did you use to check on the phone?

Unless you are the original owner and you bought the phone from an authorized Apple seller, just about anything is possible. Buying a used phone is always a roll of the dice. We ask because your phone may have been refurbished and parts from other phones were used in the remanufacturing process.

Finally, what do you see if you check Settings > General > About > Warranty Coverage?

Enter your phone's serial number here --> Check Your Service and Support Coverage - Apple Support