Original Google Pixel smartphones arrived with an 18W charger and the same goes for the new Pixel 2 lineup. Google claims up to 7 hours of mixed usage with just 15 minutes of charge, but that can be improved if you buy a compatible USB Power Delivery charger.
It seems like new Pixel 2 and Pixel 2 XL smartphones support up to 27W charging, but if you have a compatible USB Power Delivery charger, such as a charger from Pixelbook (at a lower power level). That charger is selling for $60. Hopefully more compatible chargers will be available soon.