2K released a demo of Civilization VI on Steam today. It allows the player to play for 60 turns. After that, one can either buy it or start over again.
The devs explained on Steam: "You’ll have the option to play as Qin Shi Huang on a fixed map with America, Egypt and Sumeria. You will also have the option to play the Civilization VI tutorial, which features Sumeria and Egypt. Both options are locked at 60 turns, and once you’ve reached the conclusion of the demo you will have the option to purchase Civilization VI or you can play the demo or the tutorial again. There is no limit to how many times you can play the demo."
Additionally, they released a beginner's guide featuring "top 10 tips". You can find it and the demo right here.