Yes, these are the steps. But if you run the CFGLock tool again, you can end up Locking it back if it is already unlock.
I'll explain you what to look for in order to know if is unlock or not.
View attachment 481357
Notice in this image the Variable read value is 0
0 means disable/off
1 means enable/on
The setting is a CFGLock, which means you set the Lock on or off.
If is off, like in this image, then you answer n ( you don't want to lock it)
If it's on (value 1) then type Y to unlock the CFG (This disables CFGLock)
After making sure you have the right value set, reboot, clean NVRAM if necessary, and then reboot into macOS.