Just remember to flip this switch on every app that will let you:
Android Oreo feature spotlight: You can force Android's new background limits on old apps
A few other notables about my usage:
1) I do not let email sync automatically. This is for my own sanity but it makes a difference with battery life
2) I keep BT and GPS off until I need it. This IS for battery although I think it's negligible.
3) Naptime makes a difference. You can find it on Google Play here:
https://play.google.com/store/apps/details?id=com.franco.doze&hl=en
If you are not rooted like me, you will need ADB on a computer to get it going. I think most of my long standby time is due to Naptime. When I take mine off the charger and walk away, it's still at 100% 8 or 9 hours later (if I've unplugged it at the "perfect" time). Of course, remember that the 100% range is a bit of a lie on Android and iOS.
Sorry for the rambling, I just don't want anyone to think their Pixel 2 will do this out of the box.