How to check if my AirPods Pro are genuine or not

Go to this website -> Check Your Service and Support Coverage - Apple Support

Enter the serial number of your AirPods. You can find it in your iPhone settings, AirPods package or in the charging case

After submitting, it shows the coverage of your AirPods if they are genuine

Most important question... Where or from whom did you buy them? The answer will almost assuredly determine the out come of your question. Your question already implies you did not purchase them from Apple or an authorized Apple reseller.