While attempting to set up Carplay on my iPhone 14 Pro Max, the phone locked up solid. Would not respond to touchscreen. Restarting phone didn't work. Next, pressed Volume Up, Volume Down and then held button on right side of phone until phone could be recognized by iTunes via a USB Cable. iTunes recognized the phone and its serial number and recommended Update. iOS18 was successfully downloaded and iTunes displayed that the OS installed correctly. However, after post-installation restart, phone went straight to unresponsive "Swipe up to recover" screen with white background. Would not respond properly to swipe. Made a tone, but did not recover. After several swipes, appeared to go into password entry screen. Pressing a number resulted in the phone loudly stating which number was pressed, a delay, then another loud statement about which alphanumerics that button represented. For instance, "2" resulted in "Two" being stated, a pause, then "ABC" was stated. Wow. So unimpressed. Anyway, will take it to an Apple Store (1-1/2 hours away) to see if they can strip off my files since my last iCloud backup. After that, looking at a complete Restore from iTunes. Very inconvenient and cannot locate a single person to help.
For help with CarPlay, please post in the Apple Support Community. The Apple Developer Forums are for questions about APIs and features intended specifically for developers.