The way I understand it, it is mis-named. CarPlay is the functionality that makes it possible to control and play your iPhone using the car's control, whether wirelessly or wired. The karaoke feature actually works when you login to your Apple Music account through the device's builtin Apple Music device. Then, you can display the lyrics to songs that have them on your PASSENGER display only. I don't login to my Apple Music account this way, so I have never tried it. But the feature uses Apple Music, not CarPlay.