USB-A is a port type, as is USB-C that is used with the new iPhone 15 models.
Charging this iPhone does require that any power source & charging cable you use support USB PD (power delivery). Just because the port type is USB-A does not necessarily mean that it cannot support charging. Ideally, you will want to use a USB-C adapter & cable with the iPhone 15. One option, for a car with only USB-A ports, would be a USB-A to USB-C adapter. Eventually, newer cars coming out, will be equipped with USB-C ports, and/or wireless MagSafe.
The iPhone's "charger" is actually built into the phone itself. In order for it to charge the phone's battery, it will require a sufficient amount of current from and external power adapter. For fast charging, that adapter should provide, at least, 20W of power.
Ref: Fast charge your iPhone - Apple Support