Watching the Star Wars films in chronological order means watching the movies in the order based on the sequence of events in the movies.
This is a fairly straightforward order to watch the movies in, as every movie except the two anthologies are denoted by their episodic number determining their placement in the chronological timeline of the series. Viewers would start with the prequel trilogy (Episode I: The Phantom Menace (1999), Episode II: Attack of the Clones (2002), and Episode III: Revenge of the Sith) and then the two anthology films in the following order: Solo: A Star Wars Story (2018) and Rogue One: A Star Wars Story (2016).
Finally, viewers would watch the original trilogy (Episode IV: A New Hope (1977), Episode V: The Empire Strikes Back (1980), and Episode VI: Return of the Jedi (1983)) and the sequel trilogy (Episode VII: The Force Awakens (2015), Episode VIII: The Last Jedi (2017), and Episode IX: The Rise of Skywalker).