Google decided to change things up when it came to navigating around Android, starting with Pie. Although the new "gesture" system was an optional change for updated devices, it's a mandatory part of the Pixel 3 experience. Thankfully for those that dislike Google's forced change to navigation — which has none of the space-saving advantages of iOS' gesture system — the folks at XDA have already figured out how to disable it, but you'll have to give up the Pixel Launcher.
Switching back to the old system isn't too terribly complicated, but it does require that you have ADB installed on a computer and USB Debugging enabled on your phone (Settings -> System -> About Phone -> tap build number 7 times to enable Developer options, then enable USB debugging in Settings -> System -> Advanced -> Developer options). ADB can be installed a multitude of ways, but one of the easiest methods for Linux and Mac OS is our own Corbin Davenport's Nexus Tools installer script. On Windows, those that don't wanna install Google's full Android Studio can just pull down the SDK Platform Tools separately.
Only a few steps via ADB. Image from XDA Developers.
Once you're set up for business, disabling gestures is as easy as invoking a shell via ADB on your Pixel 3 or 3 XL, uninstalling the Pixel Launcher, changing a setting that controls software navigation keys, and then rebooting. Before you do that, make sure you install another launcher. With the Pixel Launcher disabled, you'll run into issues if you don't have a replacement already available.
Once your Pixel 3 is connected and recognized by your computer via ADB, and you have a replacement launcher installed, the steps required are:
1. Open a shell in ADB:
2. Uninstall the Pixel Launcher:
pm uninstall -k --user 0 com.google.android.apps.nexuslauncher
3. Enable the old-style navigation bar:
settings put secure system_navigation_keys_enabled 1
4. Reboot via your preferred method
A simple "reboot" command via ADB can do this.
For the more detailed, full walkthrough — which includes instructions for rolling back to the gesture system, if you decide you prefer it — check out XDA's post.
If you're successful, you'll see both the old 3-button navigation bar and Google's stacked card-based recents/multitasking UI.
- XDA Developers