https://thenextweb.com/insider/2019/09/03/android-10-is-out-on-pixel-phones-and-more-heres-how-to-get-it/

Android 10 has finally landed, despite my reservations that it’s not named after a dessert. After several betas introducing everything from new gestures (again) to chat bubbles to a more pervasive dark theme, Google‘s latest OS update is rolling out to Pixel devices and a few others right now.

Though rollouts are typically gradual, you can get it right now by going to Settings > System > Advanced > System Update on your Pixel device. If it doesn’t show up, a refresh should do the trick. If you still don’t see it and are desperate for the latest software, you can sideload an OTA or flash a factory image via ADB. If those words made no sense to you, you should just wait to get the update like everyone else