1. Different plots engage the same question/issue.
One of the most prevalent issues in the Harry Potter series is the issue of prejudice. Audiences first encounter it through the Dursleys and their treatment of Harry. Because of Harry’s magical parentage, the Dursleys malign and mistreat Harry. Ironically Harry’s other main antagonists, Voldemort and his followers also begrudge Harry because of his heritage, but in their case they feel that he is “not magical enough”, since he is born of a muggle born wizard (his mother).
1. Isolating the story to a single location.
Most of the time this amounts to isolating or trapping multiple characters in a single location, which was already covered in Characters #3, focusing on characters in the same location.
1. One conflict/resolution leads to another.
In Harry Potter, particularly books 1 & 2, the overarching conflict is unraveling a mystery, (What is hidden in the castle? Who opened the Chamber?). Within this larger conflict, the characters engage and complete numerous smaller steps, some planned, while others are unexpected. As they progress, each resolution leads to the next step in the plot.
Some stories are told from a single perspective, in a single location, over a short span of time (for example, Emperor’s Soul by Brandon Sanderson), but in general, the longer a story is, the more complex it becomes. Most novels feature between 2 and 6 different point of view characters, each with their own cast of supporting characters. They engage multiple narrative threads, spanning a wide range of locations and moments in time.