Essential Phone getting new Android 8.1 Oreo update with April security patch
First off, the new Android 8.1.0 Oreo build (141) brings the April security patch, the update that's been released by Google. But that's not all that Essential Phone owners get in this update.
Some modem stability fixes have been implemented too, along with Bluetooth 5.0 certification and improved performance and bug fixes. For gamers, the update should make wonders since the Essential Phone will now handle external game controllers properly.
The OTA (over the air) rollout has already begun, so you should see a notification on your Essential Phone soon. If not, try to push it manually by heading to Settings / About Phone / Software update.