There are really just two ways to handle a "notch" display cutout in software. Either you have content stop before it would be cut off by it, or you allow it to go all the way to the display's true edge and suffer the loss of visibility.
Everyone has an opinion about which is better, but Essential just made it so we can all have our way. The Oreo 8.1 (build 141) update includes a new "Essential notch settings" that allows for per-app and global notch customization.
The new option appears in Settings -> System -> Developer options -> Essential notch settings. (If you don't see the Developer options, they likely aren't enabled yet, but we have a quick walk-through.)
You're able to set a global default setting to one of three options. "Essential recommended" follows the settings the company prefers on a per-app basis—presumably Essential has tested some applications themselves to see how they look or work with the notch. The other two options are self-explanatory: "Don't use notch area in landscape" will never render stuff under the notch in landscape mode, and "Always use notch area" will (you guessed it) always use it.
You can also apply settings on a per-app basis, in case there are only one or two apps that you'd like to have behave differently. So, for example, you could allow video to the edge of the display in Netflix, but not risk text being cut off in Kindle.
"Essential recommended" above, "Always use notch area" below. Note differences on the left side.
Unfortunately, YouTube still doesn't have the zoom-to-fill mode on the Essential PH-1 that it does on the Pixel 2 XL, so these images aren't indicative of most playback. The aspect ratio of Essential's phone interferes with using the notch, generally.
Netflix, however, has no such objections and is only too happy to cut itself off to fit.
Pardon the photo, Netflix doesn't allow screenshots.
So if there was a specific app you did or didn't want the notch to intrude upon, now it's up to you. All we need now is the same zoom support on YouTube that the Pixel 2 XL enjoys.