The iPhone XS, XS Max, and iPhone XR ship with the same standard 5W Power Adapter that's traditionally included with iPhone models. The three devices also include a standard Lightning to USB-A cable, despite the fact that Apple's current Mac lineup has been transitioned to USB-C.
Those who want to use fast charging on the new 2018 iPhones will continue to need to purchase an 18W+ power adapter and a USB-C to Lightning cable.
There are plenty of third-party 18W+ power adapters on the market (or you can get a 30W MacBook charger from Apple for $49), but Apple sells the only certified Lightning to USB-C cable at this time. Apple is planning to let other manufacturers make these cables, but third-party USB-C to Lightning cables aren't expected until next year.
With fast charging, iPhone models are able to charge to 50 percent battery life in a 30 minute time span. iPhone XS, iPhone XS Max, and iPhone XR all support fast charging.