Wanda's powers may have been used for a decidedly murderous purpose in the first episode of WandaVision - namely, to try and kill Mr. Hart. The first episode of WandaVision opens on a classic sitcom premise, where Vision and Wanda find themselves hosting a dinner for Vision's boss, Mr. Hart, and his wife, despite both heroes forgetting they were supposed to.
After a series of hijinks revolving around making a meal despite being entirely unprepared, the dinner begins, only for Mr. Hart to fall into a series of convulsions after choking on his food halfway through practically interrogating the pair. The scene lasts for a notably long time, far into the point at which viewers would become uncomfortable, especially given Hart's choking is interspersed with his wife playfully telling him to "stop it", seemingly unaware of the severity of the situation. Vision eventually comes to his boss' aid, but only after the Scarlet Witch tells him to, which raises a series of questions about what exactly went on in this scene.
Given how surreal these events are, there is one likely answer for what caused it: Wanda. Mr. Hart's fairly severe questioning is cut off by him choking, and subsequently, the topic is entirely dropped - which was what Wanda wanted to happen. It's clear that Wanda's reality-bending and matter manipulation abilities would allow her to do something like wedge food in someone's throat, and the idea she was using her powers to do this is supported by Mrs. Hart's surreal robotic reaction, not to mention Vision sitting passively by until his wife instructed him to do something. And with how long it takes Scarlet Witch to get Vision to help Hart, it's very likely she could have killed him - or possibly even intended to, at least for a minute.
Although her true intentions are somewhat hard to understand currently, given WandaVision's world and premise, as it's clear that even if she created this world reality the ground up, she doesn't seem to have any recollection of doing so. This raises an even more unsettling prospect, wherein Wanda was not aware of it, but was subconsciously using her powers to choke Mr. Hart in an attempt to stop the uncomfortable questioning from continuing. This is an even more volatile situation than if Wanda had simply meant to do it, as it would suggest the MCU hero's powers have become partially out of control, and thus she could do awful things without even knowing.
As Mr. Hart didn't die during this encounter, it's likely he will be one of the characters to appear in WandaVision again - which may shed further light on whether this whole ordeal was some surreal case of happenstance, or whether his misfortunate is a result of Wanda not appreciating his line of questioning, and - knowingly or unknowingly - punishing him for it.
