The Android 8.1 Oreo Beta OTA was just pushed out by Google yesterday afternoon, and already it's starting to makes its way to devices like the Pixel and Pixel XL, and devices such as the Nexus 6P. Not all users will have it yet, for a couple of reasons, one of them being that Google rolls out updates in stages so it's normal for these things to take some time. Not a lot of time, but usually a few days at least. The other reason is that people need to be enrolled in the beta program if they want the OTA to show up on their device.
If you're in the beta program, you may have already seen the status alert that the software was available to grab. If you haven't, it might still be available for download if you navigate to the settings menu, then to system and tap the software updates button to see if it shows up. If it does you're pretty much done, you just need to initiate the download and the process for the update will start, and hopefully complete without any issues.
Android 8.1 doesn't necessarily come with a large list of new features compared to the jump from Android 7.1 to Android 8.0, but it does have a handful of noticeable changes already, like the color matching notification shade (the quick settings menu), which will pick colors from the background to add to the transparent overlay of the shade. This is purely aesthetic, but it does look nice especially when you're in different apps as it's cool to see the color change. Another new feature is the dimming of the nav buttons, and there is even a new easter egg. For those that hated the persistent notification telling you which apps were running in the background, that notification has now been changed to tell you which apps are consuming battery, and it's now possible to disable it without using a third-party app that you would need to install from the Play Store. With the small list of changes so far that have been discovered, are you going to install the Android 8.1 Beta OTA, or will you wait for Google to properly push out the software as a final public release?