The The Fate of Atlantis - Episode 1: Fields of Elysium Add-on for Assassin's Creed Odyssey has 5 achievements worth 110 gamerscore.
Kill all Overseers in Elysium.
Remember who you are.
Destroy all of the Marble Maiden Tributes.
Collect all the Keeper's Insights in Episode 1.
Win the conquest of Elysium with freed humans from the 3 main regions.