Hello poker folks!

After a longer time of playing poker (micro SNGs back in 2015) I wanted to play poker again, MTTs it is this time.
I was going to buy the old Harrington books but I've read that they are just outdated and they should not be considered as a gameplan nowadays. There is also a new Harrington book I've seen (Harrington on Modern Tournament Poker). Is this any good? Does it require to have read the old books of him?

Where should I start learning? Any new books I should consider to buy, maybe a good pokerschool online? I would not mind to pay for a subscription. Where do new poker pros, we see on the big tourneys, learn?

I was just a microstake breakeven player but I had fun and I know the rules of poker at least. So there is no need to learn what a BB is, what UTG means etc.

Thanks in advance and gl at the tables!