https://www.gamespot.com/articles/steams-next-free-weekend-games-now-available/1100-6457622/

If you're looking for something to play this weekend, here's some good news: Steam's latest free weekend has begun, and it features The Elder Scrolls Online and F1 2017.

ESO's free weekend gives you 5 days to try out the base game; the trial will expire on March 28. In addition, if you end up wanting to buy the game, it's on sale right now for $20 (normally $30). You'll get the base game and the Morrowind expansion. It's worth noting, though, that if you think you'll want Summerset, it's still cheaper right now to buy the $40 version that comes with the base game and both expansions.