Colson Whitehead uses multiple literary devices in his award-winning 2016 novel, The Underground Railroad. Since you mentioned point of view, we'll start with that. The book is written in the third person, limited omniscient. In the opening chapters, the narrator primarily follows around the protagonist, Cora, a slave girl, but also slips into the point of view of the slave owners. For example, "Everyone knew n—ers didn't have birthdays" (11). The use of the n-word, which I don't want to write out, is important because it was the language used at the time (the 19th century) but also, I think, because it's shocking and will remind the reader of the brutal racism of the period. The literary term for word choice is diction.
Another important element of the novel is Whitehead's tone. It's easy to imagine someone writing about slavery with outrage or righteous anger, but Whitehead maintains an understated, subtle tone throughout, which I would argue makes his story even more powerful. He knows the readers will find depictions of slavery awful, and that presenting it in a relatively unadorned manner is more effective than melodrama.
Finally, there is the railroad of the title. Like many young people, when he first heard about the underground railroad, he pictured an actual railroad running underneath the earth. And he makes the railroad literal here. It's the use of an unrealistic or fantastic device to make a larger point. The reader will think about the actual railroad and conductors such as Harriet Tubman, who led slaves to freedom and so it functions as a kind of historical allusion. It also acts as a potent symbol of escape, freedom, and movement, one of the themes of the novel.