[Update #2]: Total War: Troy's Amazons DLC is charging in on September 24th and will be free for two weeks!
[Update]: Total War: Troy has been unleashed, and it is indeed entirely free to grab for the first 24 hours!
In a bit of a departure from how the rest of the series was handled, Total War: Troy will be launching this August 13th exclusively for the Epic Games Store. While this might be considered a major downside to some, it's also well worth mentioning that Troy will be entirely free to grab for 24 hours after launch!
The good news doesn't end there, however, as Creative Assembly has now announced that Troy's very first DLC will also be a freebie. So once the all-female Amazons arrive at some point this September, you'll be able to grab them for free through Total War Access, much like some of Total War: Warhammer 2's free DLCs.
When it comes to other post-launch updates, Troy will also be getting proper mod support in September, though you'll still be able to mod Troy the old fashioned way from launch. As for multiplayer, that will be coming at some point in November, though the exact details are unfortunately few and far between.
You can learn a tiny bit more about Total War: Troy, as well as the future of the Total War series as a whole, over at the official website.