I'm going to focus on epistolary narrative here. This of course comes from the Epistles, like the letters that Paul wrote to the Ephesians and Romans--an epistolary narrative is a collection of letters or journals that tell a story.
Some of the best examples of epistolary narratives are gothic or horror tales like Dracula, Frankenstein, and The Strange Case of Dr. Jekyll and Mr. Hyde. Certainly, these stories are well-known to us today, but if you can read these stories with less jadedness and cynicism that we might read contemporary stories, the narrative structure is genius. Each of these novels works like an investigation, giving the reader bits of strange information from different observers over time. This narration can feel like different evidence gathered over time, such that over the course of the novel, the reader becomes more convinced of the plot. Like in Dr. Jekyll and Mr. Hyde, the events of the brutal attacks and strange happenings come through a policeman, a maid, and a lawyer, but only in the end, with the dead Mr. Hyde's journal, can a reader fully understand the situation. The narration slowly reveals the plot, intentionally building suspense through the different points of view.
A different example of epistolary narrative is Graham Greene's The End of the Affair. The point of view is first person, a troubled writer who has fallen in love with a woman who has left him. The narrator is very self-aware of himself and his writing--but several chapters near the end are the journal that he steals from his love. He is gathering "evidence" in a sense, hiring a detective and trying to understand why she has left him. These chapters are a glimpse into her point of view.
One last example, Clarissa by Samuel Richardson. I do not really recommend this one for the modern reader. I read this one for a class, and this beast is over 1500 pages long and is from 1748. I find this one fascinating in strange ways: probably because some people really like it, the family is really messed up, and the narrative structure goes back and forth between letters and diaries. Yes, I used Clarissa and her family for my writing, and the earliest draft of Cary was in an epistolary narrative, going back and forth between emails and texts.
I quickly realized this wouldn't work.
The epistolary narrative structure is a wonderful form for revealing a story from different points of view, and in particular, telling about something that may be unbelievable and may need many witnesses and evidence for the readers to understand.
More on point of view....