It's a bit of a mix. Parts of it might draw inspiration from true incidents, but it's likely been embellished and adapted for entertainment purposes on Hulu.
Most likely, it isn't a true story. Usually, such sagas incorporate fictional elements and creative storytelling to make it more engaging and entertaining for the audience.
It was rare to see a novel with Tang Wu as the main character, but there were some novels that told the story of Tang Wu, such as Douluo Continent and Douluo Continent 2: The Legend of the Dragon King. In these novels, Tang Wu was an important character. He was a powerful soul master who had once served the soul master alliance and won many victories in the competition. He also had complicated relationships with many other characters, including Tang San's father Tang Hao.
Fortnite Story is indeed free. You can jump right in and start experiencing the story without having to pay upfront. But keep in mind that there could be optional paid elements for customization or to unlock certain extras.
Fortnite's story is set in a post-apocalyptic world where players battle to survive and build. There are various missions and events that shape the narrative.
The Fortnite story is all about survival and exploration. There are battles, hidden treasures, and a lot of mystery to uncover. It keeps evolving with each new season and update.