[2021] Schlieffen combat mission

Schlieffen will be available in EARLY ACCESS via the Lighthouse Auction section here: https://worldofwarships.com/en/news/sales-and-events/lighthouse-auction-schlieffen/
If you don't participate in the bidding for early access to the Schlieffen that is completely fine! It will become a tech tree T10 that anyone and everyone can get for free! This usually takes 2 patches from the opening of Early Access for the Tier 10 to become available.
Don't worry about things like KOTS - Schlieffen won't be allowed into King of the Sea as it is too new.