Update: The specific date of release is 8th February 2018.
The very first full expansion for Civilization VI has been announced: Rise and Fall.
Coming out in February 2018, it’ll add nine new leaders and eight new civilizations, as well as new buildings, resources, districts, wonders and units. The expansion introduces a Loyalty mechanic. Each city will have a separate loyalty rating, with high loyalty bringing bonuses and low loyalty bringing revolts and unrest.
Another new system is called Emergencies, where civilizations will be able to join up to stand up to a civilization that is becoming too strong.
You can check out the trailer below: