Good day all
Not sure if this was already asked and answered but I'm looking to upgrade from 20" iMac to a 27". My question; I would like to make an exact copy of just transfer to the new one so I don't have to reinstall everything. What is the best way to do this?

I also have 1TB external, 500MB external (using now with time machine backup), and 1TB Mystora wifi external storage. not sure of any of that will help my situation.

I am planning on selling my 20" once I have the 27" on my desk.

any info would be appreciated. Thank you