Over the past few weeks, some owners of the 2016 Pixel XL have reported problems using quick chargers on Android P. For most of that time, Android P was still in beta, so bugs were to be expected. Unfortunately, issues with quick charging are still present in the final 9.0 release.
As you may already know, all Pixel phones use USB Power Delivery (USB-PD) for quick charging. Any plug/cable/computer/battery certified for USB-PD should charge the phone at a rate of (at least) 5V/3A, and Android will show a 'Charging rapidly' message on the lock screen.Read More
2016 Pixel XL owners experiencing issues with quick chargers after Android Pie update was written by the awesome team at Android Police.