They obviously knew what to expect once the game is out and readjusted accordingly when they started working on the live content.
But you don't start working on the live-service content only
after your 1.0 launch. Or if you do, you have just... fundamentally failed the assignment.
Like I play Star Rail for example which is currently in its first anniversary update, which is the second part of a big new 2.x storyline in a big new world and during their last dev stream they said they were already working on this half a year before 1.0 even released!
Maybe I'm just spoiled by Hoyoverse games, but my understanding of making a successful live-service is that you absolutely have to already massively invest in a content-pipeline
before your 1.0 is out. If you wait until after release, to gauge the success and how much you are willing to invest into it going forward, you have already failed because you cannot increase teamsize and content output fast enough in case your game is successful
You can still scale up further based on success, but this will only be felt by players in ~year 2 and after, your year 1 plan still needs to be good enough regardless.