This claim is false.
The claim comes from Taylor Swift fans due to multiple connections between Taylor Swifts former projects, specifically All Too Well (10-minute version) and the actual Argylle book/film.
Several sources have come out to say Taylor Swift was not involved in the film. The real author of Argylle, Elly Conway stated, "I’m not Taylor Swift! We both love cats and I adore her music. I’m sure that when she writes a book she will use her name and it will be as brilliant as everything she does." However, Elly Conway is made up of Austrailian. screenwriter and novelist Terry Hayes and British author Tammy Cohen.