Hi Jen500,
Thanks for using the Apple Support Communities.
We understand that your music starts playing automatically once your iPhone connects to your car.
You've tried some great steps so far. We recommend reviewing If you need help with CarPlay to make sure you've tried those steps.
First, make sure that your country or region supports CarPlay and that your car supports CarPlay. If you're unsure if your car supports CarPlay, contact the vehicle manufacturer.
Make sure that your iPhone has the latest version of iOS. If your iPhone is updated to the latest version of iOS, follow these steps—checking CarPlay after each step:
1. Check your connection to your CarPlay stereo:
* If you have a wired connection, try connecting again with a different USB cable to a different USB port if you have one.
* If you have a wireless connection, make sure that Bluetooth is turned on on your iPhone under Settings > Bluetooth. Then go to Settings > Wi-Fi, and make sure that Wi-Fi is also turned on. Tap the CarPlay network, and check that Auto-Join is turned on.
2. If CarPlay doesn't activate automatically, look for the CarPlay logo on your car's display and select it.
3. Restart your iPhone and your car.
4. Make sure that Siri is on.
5. If your iPhone isn't detected by CarPlay, make sure that CarPlay isn't restricted. Go to Settings > Screen Time > Content & Privacy Restrictions. If Content & Privacy Restrictions is on, tap Allowed Apps, and make sure that CarPlay is enabled.
6 Go to Settings > General > CarPlay, tap your car, then tap Forget This Car. Then set up CarPlay again.
7 Make sure that your CarPlay stereo is using the latest firmware from the car manufacturer. Check your car's manual for more information.
The reason why we are recommending the steps above is because they will show you what to do if CarPlay doesn't work like you expect.
If you're still experiencing the same issue, contact Apple Support.
Cheers!