Some names can be difficult for Siri to get right on its first try. It used to be easier to get this done, but here's how to teach Siri correct pronunciation of names in iOS 15
While you used to be able to verbally coach Siri on how to pronounce a contact's name, that's not the case in iOS 15. Now, you'll need to resort to adding in a phonetic guide directly.
Select the contact you wish to add a phonetic guide for
Scroll down, then tap Add Field
Tap Phonetic first, middle or last name
In the Phonetic Name enter in a phonetic spelling of your contact's chosen name
It may take you a little while to figure out how to phonetically spell someone's last name, as Siri doesn't always seem to pronounce certain sounds the same way consistently.