High battery drain on Nexus 6P with Pixel Experience
Have you tried Greenify? It's on Google Play Store. Install it and grant root permissions. You can read about it here: https://forum.xda-developers.com/apps/greenify

You can also try to flash Derp Kernel

Credit to https://www.reddit.com/r/PocoPhones/comments/askuec/pixel_experience_battery_drain/