General information about the power supply
The iPhone XS Max comes with the standard 5W USB Changer. One thing that is interesting is the power adapter doesn't have the green sticker on the back any more.
See this side-by-side comparison with the Adapter that came with my iPhone 6s Plus when I purchased it back in September 2015.
Why the Green Dot?
According to Apple, the green dot was put on the Power Adapter by Apple to show that the plug isn't part of the Exchange program. See full details on the Apple Exchange Program page.
Is 5W Enough?
As mentioned in a previous blog post, 5W might be a good option for overnight charging. However if your traveling a lot you should consider investing in a more powerful charger that will charge the iPhone XS Max in about 1/2 the time.
Ideally getting a 12w or more powerful charger will be helpful when you need a quick boot for those crazy Saturday routines.
If your looking for a unique gift idea for "someone that has everything" get a USB-C charger with a USB-C to Lighting Cable. According to Apple this will fully charge the iPhone XS Max in about 1/2 the time.