How The Force Awakens Tried to Kill a Sith and Failed
The Force Awakens attempted to escape the Jedi-Sith binary; however, The Rise of Skywalker proved this impossible.

The duality of the Force, the light side and the dark side, has been prevalent in Star Wars media since the premiere of Star Wars IV: A New Hope, but the first film in the sequel trilogy, Star Wars Episode VII: The Force Awakens , trying to escape this duality, but without success. In addition to the light/dark theme popular in Star Wars, it also introduced audiences to the Jedi Order and their enemies, the Sith. While the Sith wasn't too prominent in the original trilogy, the prequels were.
The prequels need to focus on the Sith and Sith Lords to better understand the fallout and dark side of Anakin Skywalker's fall to the Sith. While the prequels exceeded expectations in showing the power of the dark side, it also made the Star Wars media very dependent on the Sith Lords and their Jedi Knights. When it came time to start making the sequel films, there was an effort to move away from the Jedi and Sith binary that audiences had grown accustomed to.
How Force Awakens Tried To Ignore The Sith

The Force Awakens made many efforts to move away from the Sith story and focus primarily on the Jedi. guide JJ Abrams denies that both Kylo Ren (Ben Solo) and Supreme Leader Snoke are Sith Lords. That doesn't make much sense, since both Kylo Ren and Snoke have attributes that are closely related to the Sith. For example, Ren wields a red lightsaber, in typical Sith fashion. Also, when Rey, Han Solo, Chewie, and Finn meet Maz Kanata, she talks about the Sith as if they're a thing of the past.
Killing The Sith Was Part Of Star Wars' Prequel Rollback

Staying away from the Sith in The Force Awakens is intentional. In an attempt to set itself apart from the prequel films that were considered mediocre at the time, the first installment of the sequel purposefully differentiated itself from the Sith. Because the prequels were so focused on the Sith, especially Anakin Skywalker's turn to the dark side, the sequel initially tried to focus on other things.
At the time, there was plenty of Star Wars media featuring Sith as main characters, such as the Clone Wars cartoons. The Clone Wars explored the Jedi Order between the two prequel films, making it as reliant on Sith features as the films. The Force Awakens Tries to Bring Something New to Star Wars, but the trilogy eventually returns to its roots, featuring Sith vs. Jedi in later films.
The Rise Of Skywalker Undid The Force Awakens' Sith Change

Star Wars Episode IX: The Rise of Skywalker overturns previous claims that the Sith have been wiped out. A lot of movies revolve around the Sith and their secrets. Rey, Poe, Finn, Chewie, C-3PO, and BB-8 find the dagger. The inscription on the dagger is in an ancient Sith language that only C-3PO can understand. The Rise of Skywalker also has Sith Pathfinders from the wreckage of the second Death Star. Not to mention the return of Sith Lord Darth Sidious (also known as former Emperor Palpatine). The movie's plot revolves around Palpatine's return and how to stop him and Kylo Ren from taking over the galaxy with the Final Order.
The Rise of Skywalker brought the Sith back to the forefront of Star Wars by bringing back Palpatine and making Ray Palpatine his granddaughter. Not only did they bring back the most powerful Sith Lord the audience had ever seen, but they also brought back more questions about the Sith. also, The Sith Temple has been seen before in Star Wars Rebels, but the one seen on Exegor seems to be more about the Sith than the one seen in Rebels in Malachor future.
While The Force Awakens isn't the best Star Wars movie, it does try to do something different and bring new voices to the galaxy beyond just Sith and Jedi. However, the fact that neither Kylo Ren nor Supreme Leader Snoke are considered part of the Sith is confusing and doesn't make much sense. Because of this, the other two films in the trilogy try to address this issue, and The Rise of Skywalker completely undoes what The Force Awakens did in getting rid of the Sith.