iPhone XS and iPhone XS Max require a Mac running at least OS X El Capitan 10.11.6 or later and iTunes 12.8 or later to sync and back up with iTunes.
To upgrade iTunes, use these steps:
- If it's open, quit iTunes.
- If your iOS device is connected to your Mac using USB, disconnect the cord.
- Download iTunes 12.8 from Apple and install it on your Mac.
- Unlock your iOS device, and while the home screen is visible, reconnect it to your Mac using USB.
- Open iTunes.
- When you see a message that says "A software update is required to connect to this [device]," click Install. Learn more about what to do when you see this message.
Get more help if iTunes still doesn't recognize your device.