Where is Sync on Bluetooth Menu iPhone 7

Never paired with a vehicle but with Bluetooth headset and speaker one place the speaker, headset and maybe vehicle into pairing mode how ones does this is usually described in a manual or on the site of the manufacturer

There is no such thing.

The device is listed in the bluetooth list, you select the listing to pair.

Once paired, if you want to sync contacts that is done on the car system.

Read the car's manual to find how to put your system into pairing mode.