This rumor is not completely confirmed, however, but rather comes from The Hollywood Reporter, which cites unknown sources about the news.
Despite having a long and storied career, few would deny that Lando Calrissian is Williams’ most famous role. The lovable con artist premiered in Star Wars: The Empire Strikes Back as an old acquaintance of Han Solo (played in that film by Harrison Ford), who is forced by circumstances to betray his old friend to Darth Vader. Nevertheless he helps the rest of our heroes escape, and works with them to recover Han and fight the Empire in Return of the Jedi.
Williams has gone on to voice the character in later Star Wars media, such as video games, the canonical cartoon Star Wars Rebels and even in parodies like Robot Chicken. While usually in a secondary role, he has become quite popular, both for being the first black character in the franchise and for his suave, charming personality (in contrast to the perpetually grumpy Han).
So far, Calrissian has been one of the only major characters absent from the Sequel Trilogy, so many fans were expecting/hoping for him to appear. This is especially the case since (spoiler alert?) neither Han, Luke nor Leia will be in Episode IX; as the unofficial fourth member of their trio, Lando can now stand in as the film’s main connection to the past.
What his role will be remains to be seen. At 81 years old, Williams may not be up for a lot of intense action scenes, and his character was never too much of a fighter anyway; he could get a chance to fly the Millennium Falcon (which he originally owned) again. Perhaps he will have an encounter with Kylo Ren, who use to call him “Uncle Lando” back when he was a kid.
Interest in Lando has been renewed since Solo came out a few months ago; despite that movie’s box office failure and merely “okay” reviews, the younger Lando (played by Donald Glover) was one of the highlights of the film. There was talk of giving him a spin-off, though that, and other Anthology projects, now seem to be on hold.