Hi, you can reset all settings on your phone, go to Settings > General > Reset > Reset All Settings.
Force restart your phone: Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Side button until you see the Apple logo.
If the issue persists, you can restore your phone as new:
How to back up your iPhone, iPad, and iPod touch
Restore your iPhone, iPad, or iPod to factory settings
Forget your phone from the car kit & also forget your car kit from your phone, go to Settings > Bluetooth.
Rename your phone, go to Settings > General > About & change the name. Connect/pair your phone to your car again.
You can also call Apple Support: Contact Apple for support and service