In order to unlock bootloader, some phones will require OEM unlock option enabled

Click on "Settings" in phone Menu

Scroll down until you see "About phone" menu, tap once on it

Locate line: "Build number", tap it multiple times until you see "Developer mode activated" on phone screen

Go back to previous setting window or directly into "Settings" from menu. New selection will be visible - "Developer options", tap once on it

Locate "Enable OEM unlock", in order for FRP status to show up as "Unlock" this option must be enabled, so tap once on it

Confirmation window may appear, read it and click "Enable" to complete action