Stranger Things season 4’s trailer sees Max levitating in the air, hinting the teen now has supernatural powers. Since Eleven lost her powers at the end of Stranger Things season 3, the series was left without a major human character with elevated abilities. While Eleven got her powers from various tests at Hawkins Lab, Max’s apparent gaining of supernatural powers seems to be leaning into the new, even darker angle of Stranger Things season 4.
Toward the beginning of Stranger Things season 4’s official trailer, Max is seen sitting alone at Billy’s grave reading a letter she wrote to him about how different the world has been since he died. Shortly after, the trailer sees Max back at Billy’s grave alongside Steve, Dustin, and Lucas, where the latter character hugs her before (or more likely in the series after) she mysteriously levitates into the air. When Max flies into the air, the Stranger Things boys start to reasonably become frantic, with it being unclear what exactly caused this ability.
There are a few explanations as to why Max can now fly in the air, with a new gaining of powers still being in the realm of possibilities. Stranger Things season 4’s official trailer dedicates significant time to Max’s character, as she’s often seen at Billy’s grave, running through the new Upside Down locations, and exploring a grandfather clock identical to Creel House's on her own. Since Creel House’s grandfather clock is assumed to be a portal to the Upside Down, perhaps Max exploring it on her own led to some reaction that granted her powers, which may have been augmented when visiting Billy’s grave, who was notably possessed by the Upside Down's Mind Flayer in Stranger Things season 3.
However, while powers would possibly mean Max is becoming the new Eleven, her levitation in Stranger Things season 4’s trailer appears to be more connected to the paranormal angle of the new installment. Max is only seen levitating outside of Billy Hargrove’s burial place, which suggests he could be possessing her from beyond the grave. Stranger Things season 4’s Creel House has hinted at a more haunted, scarier angle to the series, which means possessions and paranormal manipulations in the ilk of The Exorcist or Poltergeist. While Billy is dead in Stranger Things season 4, his spirit may have been preserved by some supernatural ability of the Mind Flayer, which could possibly be controlling Max while she’s at his grave.
Eleven had a wide range of powers in Stranger Things’ series, but one ability she was never shown to have on command is self-levitation. She could use her telekinesis to make other objects fly and move, which may be what the Mind Flayer is doing to Max, but as far as Stranger Things has depicted, she could only slightly levitate when using her other powers strenuously. As such, this would be a brand new power for Max if she truly can make herself fly, perhaps proving her abilities could outweigh even those of Eleven. Since Stranger Things season 4’s official trailer seemed to be playing up Max’s new connection to the Upside Down, it seems more likely that her levitation is a byproduct of Billy or the Mind Flayer controlling her from his gave. If so, perhaps Max finding the grandfather clock in what appears to be the school sealed such an attachment.