The main motive for Google's pixel series is the software. It rocks a clean version of Stock Android instead of a heavy OEM skin like TouchWiz, it receives frequent prompt OS updates, the camera software is downright amazing, and it may have the smoothest UI on any phone. But one underrated benefit of the software is how easy it is to modify it with root-level optimizations.
The first step in modding any phone today is unlocking the bootloader. This allows you to flash custom images such as TWRP or a Magisk-enabled kernel, allowing you to root your phone or install a custom ROM. If you want to roud, or if you think you're rooting in the future, you should unlock your bootloader early to make sure you're ready for any upcoming mods.
Before You Begin
You should know that unlocking the Bootloader does not invalidate your Pixel 3 or 3 XL warranty. You can even undo this process and restore your phone to its original state.
Second, the process of unlocking the bootloader clears your phone's memory for security. Therefore, you should back up all your important files before you start (remember, however, that photos are automatically backed up with Google Photos.)
After all, you need two things besides your phone: Windows, Mac, or Linux computers and a USB port. data cable. Make sure the data cable is in good condition and has no visible damage.
First, open the Settings app, then scroll down and choose System from the following screen. Next, scroll all the way to the end of the next screen and find the entry "build number". Tap this item seven times in a row, and you'll see a message saying, "You're a developer now!" This means that you have unlocked the hidden Developer Options menu.
Step 2: Enable OEM Unlock  Now go back to Settings -> System, but this time tap on the "Advanced" option. This will expand the menu to show more options. Scroll to the bottom of the list and select Developer Options. From there, tap the "OEM Unlock" option to turn it on, press "OK" in the popup and enter your PIN or password.
From here the mass The remaining work is done with a computer with fastboot commands. To send fastboot commands to your phone, you need to put it into bootloader mode.
To do this, long press the power button to bring up the power menu. Select "Reboot," then immediately press the volume control on the side of the phone. Hold down the key until you reach a screen that looks like the one below – that's the bootloader mode. Just leave the phone on this screen and connect it to your computer with a USB data cable.
You now need a small piece of software on your computer to send commands to your phone. Google's SDK platform tools are now available as a stand-alone download, so it's not as complicated as in the past. Simply download the ZIP file for your operating system via the following link and move the ZIP file to your desktop.
Next you need a command prompt or a terminal window in the platform-tools folder open that you just extracted to your desktop. To do this, you need to know the full location of the platform-tools folder.
If you are using Windows, open the platform-tools folder on your desktop, and then click the bar at the top of the Explorer window to see the location of the folder. Copy this to your clipboard.
If you're on the Mac, open the platform-tools folder and then open one of the other folders in it. Right-click an empty field and select Get Info. Select the text to the right of the "Where" box, right-click and copy it.
If you are using Linux, open the platform-tools folder on your desktop, right-click on an empty space and select "Open in terminal."
Now it's time to open a Command Prompt or Terminal window. If you are using Linux, you can proceed to the next step.
If you are using Windows, press the Windows key on your keyboard, type "cmd" and press Enter. If you're on the Mac, open Spotlight Search by simultaneously pressing the Command and Spacebar, then typing "terminal" and pressing Enter.
Next, go to the platform-tools directory, type "cd" at the command prompt, and then add a space. Finally, paste the previously copied location of the file, and then press Enter.
Now type the following command at the command prompt or in the Terminal window to check the fastboot connection:  Fastboot Devices
On Mac or Linux, you may receive an error after sending the above command. If so, send them instead:
./ fastboot devices
This should return a series of letters and numbers followed by the word "fastboot". If so, then you can go well. If you have errors, read our guide to setting up ADB and fastboot for further help.
Now issue the following command to start the bootloader unlock process:
fastboot flashing unlock
If you are using Mac or Linux , you may get an error with the above command. If so, enter the following command instead:
./ fastboot flashes unlock
Your phone will display a new menu , Use the volume keys to highlight Unlock Bootloader, then press the power button to select it. Your screen goes black for about 5 seconds, then the bootloader menu reappears. In this case, press the power button to reboot the phone back to Android.