Presumably this temporal manipulation could be extended to not allow the Eye’s user to actually travel to the past and future, and from there, as this Peggy Carter hypothesizes, the user could bring a person from a different time period with them back to the present.
Or perhaps the Eye’s user doesn’t even need to travel to another period to bring a person back, and can instead just think about a deceased individual from their past to make them appear.
Either way, both Wong and Mordo said in Doctor Strange that using the Eye is contrary to the natural order of thing, so bringing back Peggy, let alone any dead person, is extremely risky.
Thus far we’ve seen the Time Stone be used to rewind and fast-forward time like a video, as well as repeat the same moment over and over again Groundhog Day-style.