I bought a Chinese version of Nokia 7 plus from this
https://www.ozbargain.com.au/node/386139
Now, I'd like to convert it to Global version.
There is a link at XDA on how to do this.
I am not sure this works, and what software I should use to root the device before following those instructions.
Any advice is highly appreciated. Thanks.
Doesn't look like you need to root the device.
Root directory means main folder.
Open dialler and Dial ##874## to update.
After you updated to Android P, you can either enjoy Android P Beta or downgrade to B2N-213B-0-00WW-B05-update.zip with the same method. Remember downgrade to B2N-213B will erase data.