One Piece Film: RED is probably the most like the series out of all the movies, but it has a lot of parts that don’t make sense.
After how well One Piece Film: RED did, fans have been wondering if it should be considered canon since it has close ties to many important characters in the main series, especially Red-Haired Shanks. With flashbacks, retcons, and characters who were thought to be dead coming back to life, it’s hard to answer the question, but let’s try anyway.
Most One Piece movies take place outside of the main timeline of the manga and anime, so they are not canon. But the most important movies have tried to stay in a gray area, caring just enough about the series’ continuity to avoid clear contradictions and conflicts.
One Piece Film: RED has a hard time with this because the manga just finished what might be its most important story arc ever, and the anime isn’t far behind. The movie could take place right before or right after the Wano Country Arc, but there are a few things that go against each other that make it hard to tell which one is true.
One of the best things about the movie is that it promises to show more about Red-Haired Shanks, who is one of the most mysterious characters in the series. A lot has been said about how Yonko and his crew will be in the movie, as well as how one of the main characters, Uta, is Shanks’ daughter.
There’s no reason to think that these parts of the story aren’t canon, and the same goes for Uta’s childhood friendship with Luffy. This makes the movie even more connected to the main One Piece series. But the movie’s timeline calls all of this into question.

RED should take place after the Wano Country Arc based on how the Straw Hat Pirates are doing. Jinbe is a member of the crew, but he didn’t join for good until Wano.
Zoro uses his new sword, Enma, and, most importantly, Luffy is known as a Yonko, a title he got after beating Kaido. Luffy also uses his new form, Gear Fifth, which he got during that battle, for a short time in the movie. But Big Mom briefly shows up in One Piece Film: RED, alive and well in her kingdom of Totto Land.
This shouldn’t be possible, since Trafalgar Law and Eustass Kid beat and killed her in an epic battle in Wano while Luffy was dealing with Kaido. This is hard to explain, and it could be a hint that Big Mom will come back in the future, but for now, it just makes the timeline of One Piece Film: RED more confusing.
It’s important to keep in mind that the One Piece movies are not the same as the manga or the anime. Even though Eiichiro Oda is in charge and has been directly involved in the last few movies, the screenwriters, directors, and producers have a lot of freedom to do their jobs.
This means that One Piece Film: RED will never fit perfectly into the series’ timeline, but most of its story should be thought of as canon.