If you relock the bootloader while on a custom ROM, you will hard brick your phone (Qualcomm EDL mode required). Only relock after flashing the official stock ROM via Mi Flash Tool.
This will show you the "Device unlocked" status (true or false). how to unlock bootloader in xiaomi poco x3 pro new
You will need an active Xiaomi account. When you create it, make sure you: If you relock the bootloader while on a