After Star Wars: The Last Jedi, there are still many unanswered questions. For example, how the resistance continues, how the story unfolds between Rey and Kylo Ren, and many more topics.
At least some of them could have an answer from the Reddit user FOOSLS. The user claims that he has read an early story script and summarizes the most important findings from it.
The events of Episode IX seem to be playing five years after The Last Jedi. The Resistance has barely any allies and the First Order is building its supremacy in the galaxy – with Kylo Ren as supreme commander. Hope in the ranks of resistance is dwindling. However, Rey, Poe, Leia and Finn do not give up hope and learn of a mole in the ranks of the First Order. From this informant you will learn about unknown regions in the galaxy where a secret planet is hidden. On this planet should be a child prodigy that allows the resistance to navigate through those same areas. The entire planet is covered by a vast ocean under which the inhabitants work as forced laborers in a manufacturing facility. The Resistance wants to free these workers to show the remaining planetary systems in the unknown regions, for which the First Order is ready. Allied with the new planetary systems, resistance once again goes to war. In the meantime, Kylo Ren and the Knights of Ren are trying to locate the traitor in their own ranks and eventually encounter General Hux. He wants to overthrow Kylo Ren to be himself at the head of the First Order. By now, the bond between Kylo and Rey is so strong that they can manifest themselves through power. It becomes clear that Rey and Kylo love each other, but keep this love secret. Many of the gifted children have now found protection with Rey. One of these children seems to be her own, after which Kylo almost kills her, but at the last second is prevented by his mother Leia.
It sounds like the film will borrow a significant plot point from the non-canon Knights of the Old Republic era, specifically a superpowered weapon used by Darth Revan during the Jedi Civil War that took place almost 4,000 years before the Battle of Yavin in A New Hope. Now before you start shouting BS, it should be noted that this is the same Reddit user who had claimed to see storyboards from The Last Jedi and in fact most of his story was accurate. That being said this should all still be taken with a grain of salt as the movie is still in various stages of development/production. Also the sad passing of Carrie Fisher may very well affect this supposed storyboard.