I'm using MacBook Pro late 2013. I want to update my MacBook to Big Sur but macbook's screen is broken.
Can I mirror my MacBook screen to external monitor while updating?
You can use clamshell mode potentially with an external monitor, keyboard, and mouse; see this thread. Or you could unplug the LVDS cable so the MacBook Pro defaults the display output to the external display without closing the laptop. However, this means opening it up.