As a disclaimer some of the books listed relate to things that happen in later seasons, so might be seen as potential spoilers for the show.
Parallel by Claudia Lefeve
Destiny has a way of catching up. Saddled with powers she doesn't understand, Etta Fleming's world is turned upside-down the day she meets Cooper Everett, the man who transports her to an alternate reality. A reality she was meant to be a part of.
One minute, she's an orphan living at Dominion House for Girls, an institution for delinquent foster kids, then finds herself attending the exclusive Dominion Hall Academy. Plucked from the only world she's ever known, Etta now has to deal with an aunt she never knew, a boyfriend she doesn't know, and a best friend who can't know.
Miss Peregrine’s Home for Peculiar Children by Ransom Riggs
A mysterious island. An abandoned orphanage. And a strange collection of very curious photographs. It all waits to be discovered in Miss Peregrine's Home for Peculiar Children, an unforgettable novel that mixes fiction and photography in a thrilling reading experience. As our story opens, a horrific family tragedy sets sixteen-year-old Jacob journeying to a remote island off the coast of Wales, where he discovers the crumbling ruins of Miss Peregrine's Home for Peculiar Children. As Jacob explores its abandoned bedrooms and hallways, it becomes clear that the children who once lived here - one of whom was his own grandfather - were more than just peculiar. They may have been dangerous. They may have been quarantined on a desolate island for good reason. And somehow - impossible though it seems - they may still be alive.
11/22/63 by Stephen King
If you had the chance to change the course of history, would you? Would the consequences be worth it? Jake Epping is a thirty-five-year-old high school English teacher in Lisbon Falls, Maine, who teaches adults for extra money. One student submits a gruesome, harrowing first-person essay about the night 50 years ago when Harry Dunning’s father came home and killed his mother, his sister, and his brother with a hammer. Harry escaped with a smashed leg, as evidenced by his crooked walk.
Not much later, Jake’s friend Al, who runs the local diner, divulges a secret: his storeroom is a portal to 1958. He enlists Jake on an insane — and insanely possible — mission to try to prevent the 11/22/1963 J.F. Kennedy assassination. So begins Jake’s new life as George Amberson and his new world of Elvis and JFK, of big American cars and sock hops, of a troubled loner named Lee Harvey Oswald and a beautiful high school librarian named Sadie Dunhill, who becomes the love of Jake’s life—a life that transgresses all the normal rules of time.
Timeline by Michael Crichton
In an Arizona desert a man wanders in a daze, speaking words that make no sense. Within twenty-four hours he is dead, his body swiftly cremated by his only known associates. Halfway around the world archaeologists make a shocking discovery at a medieval site. Suddenly they are swept off to the headquarters of a secretive multinational corporation that has developed an astounding technology. Now this group is about to get a chance not to study the past but to enter it. And with history opened to the present, the dead awakened to the living, these men and women will soon find themselves fighting for their very survival–six hundred years ago.