Firaxis and 2K games have announced that the Long War 2 mod for XCOM 2 is now available to download through Steam Workshop. This mod adds missions whose difficulty is determined by squad size as well as outside factors such as the Resistance strength in different regions around the world, along with how much presence Advent has. The Long War 2 hasn’t been confirmed for PS4 and Xbox One, though it can’t be completely ruled out as both consoles have opened up a bit to the modding scene.
If you own XCOM 2 on PC then you can grab the Long War 2 mod from here.
Source: Press Release