If you have CarPlay set up to work with Siri, you can allow Apple’s personal digital assistant to announce messages on iPhones running iOS 15 and later.
To enable Siri to announce incoming text messages in CarPlay, navigate to Settings > Siri & Search on your iPhone. Then, turn on “Announce Notifications”. Within that, you can customize which apps announce messages, including the Messages app. Ensure that “Announce New Message” is enabled for the Messages app. You can also enable/disable Announce Messages directly in CarPlay by tapping Announce when Siri reads a new message.
