If your goal is to actually unlock the bootloader (not just look at it), you must enable this setting. If this setting is missing or greyed out, your carrier may have blocked unlocking.

Alternatively, you can try the hardware key combination (if ADB is not working):

: Release both buttons as soon as you see text on the screen.

Do not proceed unless you understand the risks.

Once inside bootloader mode, you will see a screen similar to this:

Factory resetting (Wipe Data), clearing cache, manual updates. Important Note on Unlocking the Bootloader

You will see a menu with options like “Start,” “Restart bootloader,” “Recovery mode,” or “Power off.” Use the volume keys to navigate. If you see “FASTBOOT mode” at the top, you have successfully entered bootloader mode.

adb reboot bootloader