Since Red Sonja has only recently locked down its screenwriter, there aren't many details about the story available. Thankfully, director Joel Soloway gave fans a couple of hints about how the film will incorporate elements of the comic book series that spans decades.
Soloway said that Red Sonja "is an ancient heroine with an epic calling, and translating that to the screen is a dream come true for me as a filmmaker."
Millennium co-president Jonathan Younger added, "Having Joey Soloway at the helm of this feminist icon franchise is the perfect recipe for a magical adventure, which is exactly what the world needs today." Soloway's reference to Red Sonja's status as an ancient heroine could refer to the film's setting, the fictional antiquity of the Hyborian Age. The Hyborian Age was first established by Robert E. Howard, creator of the character Conan the Barbarian, and is loosely defined as a period sometime after the sinking of Atlantis and before recorded history — which is a pretty broad timeframe, but definitely ancient.
Magic is present in the Hyborian Age but rare, although Red Sonja does receive a blessing from the gods giving her unparalleled skills with her weapons. If Younger's comments about a "magical journey" are to be taken at face value, then Red Sonja might also explore that origin story.