What are some literary devices in Boy Erased?

Each time he walked past us, the shadow of the door’s central rail passed over him like the sluggish pendulum of a metronome, marking the slow tempo of his pacing.

In this first quotation here is a simile. John Smid, at this point in the story, is addressing the therapy group. The simile comparing the shadow to "the sluggish pendulum of a metronome" alludes to Smid's practiced, deliberate, methodical manner of speaking. He speaks like a priest delivering a sermon.

. . . a heavy silence blanketing the room during our morning Quiet Time, drifting into our daily activities

In this second quotation, the metaphorical image of silence as a "heavy" blanket suggests the oppressive atmosphere of a Love in Action facility. The blanket metaphor suggests that the silence is smothering and restrictive.

Masculine meant strong. Masculine meant straight. If we could only learn the essence of what it meant to be masculine, then we could learn the rest.

In this third quotation, there is repetition of the word "Masculine." By repeating the word "masculine," masculinity as a concept, and any meaning attached to it, becomes almost meaningless. It is repeated so much that it almost becomes a nonsense word, which of course it is in this context. It is nonsensical that masculinity should be synonymous with strength or, indeed, with being "straight."