Splatoon 2 is getting a paid DLC expansion in the form of the aptly named Octo Expansion. Going for $19.99, the new campaign will allow players to finally play as an Octoling in the Splatoon series. Pre-orders (which are available now) will unlock gear that you can use right away.
The campaign will feature 80+ single-player missions with a new underground hub, some returning characters from the original Splatoon and will follow the plot of Agent 8, an amnesiac Octoling. Beating the campaign will unlock the Octoling's for multiplayer use.
In addition to that, a 3.0 update will be coming to the game and include 100+ new gear items and a couple of new stages for multiplayer. The most notable feature is that a new "Rank X" will be available to grind out, pushing the level cap beyond S+, but two stages from the original Splatoon will be making a come back. The returning maps are Piranha Pit and Camp Triggerfish with Wahoo World being the new one. The 3.0 content should be ready in April.
via destructoid https://www.destructoid.com/splatoon-2-is-getting-an-octo-campaign-dlc-493367.phtml