This depends on how the plot manipulation is treated in the fiction you're analyzing, and how the hypothetical match-up scenario you want to imagine treats it. If a character is portrayed as unable to use plot manipulation outside of their own world, then it's reasonable for someone to argue against the idea that the character can use it if the battle takes place outside of that location, but this doesn't mean that plot manipulation in general works this way. There's also nothing generally wrong with allowing a character to use their plot manipulation despite a caveat, for the sake of an interesting match-up, as long as it's clarified in the battle conditions. The information in
the Reality Equalization page might be useful for you to know, because sometimes people argue that characters who are more real than a plot manipulation user are immune, despite that maybe not aligning with the kind of match-up you're trying to discuss about.