Via nerdist -
Possible Spoilers Ahead
Details are still pretty sparse on the X-Men: Dark Phoenix front. In fact, all we know is that it will borrow elements from the comic story of the same name, and that most of the cast is set to reprise their roles from previous X-Men films. However, today we have some new possible tid-bits of information that focus on Magneto, and a new location.
The new rumors come from The Nerdist, who have heard two separate reports. Both are Magneto-centric and are as follows:
Magneto will be getting a costume change. I know the characters get a costume change in every new instalment, but this one is said to draw specific inspiration. According to the report the costume is, "meant to suggest the imagery commonly associated with cult leaders."
Also, Nerdist is reporting that the film will feature Genosha. For those unfamiliar, Genosha is a fictional country off the coast of Africa in the X-Men comics. In the 90's Magneto seized control of the island, making it the new Mutant homeland before it was eventually wiped out by Sentinels.
Keep in mind, nothing here had been confirmed and should be taken as rumor for now.