CarPlay and Bluetooth connection

Jeep does not support Wireless Carplay over Bluetooth in their vehicles.

For Carplay to work, the iPhone needs to be connected to the USB port.

Consult the Cherokee's users manual.

Let's start with the basics: check and see if the Grand Cherokee needs a software update here: https://www.driveuconnect.com/support/software-update.html

It may be brand new, but the software that's installed in it may be much older.