Not entirely. 'The Keepers' likely takes inspiration from real incidents but incorporates fictional aspects to make the story more engaging and compelling.
Well, it might be about the characters in the 'Keeper of the Lost Cities' using texting to communicate. Maybe they text to share secrets about the lost cities, or to plan their adventures. For example, Sophie could text Fitz about a new discovery she made in one of the hidden places in the lost cities.
I'm not entirely sure as I haven't read it in detail. But generally, it might be about Tam's unique experiences, his relationships with other characters in the 'Keeper of the Lost Cities' world, and perhaps his adventures or challenges he faces.