The last time I started the game the content drop wasn't available, I'll do it later (without being connected to the internet, so that the game can't connect to their server) and report. Good question, btw!
Thanks for checking, it'll be interesting to read your results. Unfortunately i was connected online when i played it yesterday. I think i remember seeing the new content when i played either yesterday or maybe even the day before. So this content might have been added to the GOG version 2 or more days before the patch notes that were just posted on the GOG version today. Not sure when the last time you played while connected to the internet but you might already have the new cosmetics without realizing. I didn't get any sort of alert about it i was just looking around in my stash and saw them.
The content is there for me too. And you're right, they could have unlocked it a few days before. Someone should try to use an offline installer (which has not been updated) and start a new game fully offline, to be really sure. Or we could just get a technical answer from Techland. But I think that the newer installers (as soon as a new update comes) will contain everything previously released anyway.