A demo will also be available on the same date. While Ubisoft did not officially announce the demo, a listing with the date is already up on the Microsoft Store and the demo was also uploaded to the PlayStation Network backend.
Here is an overview of the downloadable content, via the Microsoft Store:
Expand your Immortals Fenyx Rising adventure with this first downloadable content for more epic adventures and puzzles!
In “A New God,” play as Fenyx to overcome the trials of the gods of Olympos. In these trials, Fenyx hones her godly powers and finds ways to become even stronger as they attempt to earn a place among the inner circle of the Pantheon.