Settings - System - About phone - Build number
Tap Build number until developer options are enabled
This will erase everything on your phone. All data will be lost. Make sure you copy everything you value off of the phone. The phone will be restored to factory settings.Instructions for unlocking from Essential
Turn on OEM Unlocking
Settings - System - Developer options - OEM Unlocking
Settings - System - Developer options - Automatic System updates
If you are planning to root your phone with Magisk, updates will fail unless Magisk is disabled before attempting to update. Disabling auto updates will result in a notification when updates are ready so we can install them after Magisk is disabled.
Settings - System - Developer options - USB debugging
Connect your phone to your computer with a USB cable and give your computer permission to do USB debugging with your phone.
Settings - Security - Screen Lock - None
If you forget to unlock your phone before you do the next steps you will have to reflash your boot image to stock, reboot your phone, turn off the lock screen and start over.
From you computer type this command:
sudo adb reboot bootloader
Or reboot phone while holding down the volume down button.
The benefit of doing it with the adb command is you can make sure your phone is connected and willing to accept those commands.
Run this command:
sudo fastboot flashing unlock
Use the volume button to select "Yes" and press the power button.
The instructions for unlocking your bootloader on Essential's site tell you to relock your bootloader. If you are doing any modifications DO NOT RELOCK IT unless you have restored the phone to 100% stock by flashing an image from Essential's site.