Go to settings -> sounds and haptics -> headphone safety -> lightning adapters -> reset all adapters -> unplug and plug into your car -> and then plug in, there should be a prompt for headphones or other device, select other device
Go to settings -> sounds and haptics -> headphone safety -> lightning adapters -> reset all adapters -> unplug and plug into your car -> and then plug in, there should be a prompt for headphones or other device, select other device