The reader's point of view can create suspense and humor primarily through the second option: A reader might know things that the characters do not.
When readers are privy to information that the characters are unaware of, it can lead to suspense as they anticipate how the characters will react when they eventually discover the truth. For example, if a reader knows that a character is walking into a trap while the character remains oblivious, this creates a tense buildup as the reader awaits the moment of realization.
On the other hand, this same dynamic can also generate humor. If the reader knows a misunderstanding or a comedic situation that the characters do not, it can create a sense of irony or absurdity. For instance, when characters take actions based on incorrect assumptions, and the reader can see the folly of those actions, it can lead to laughter. In both cases, the gap between the reader's knowledge and the characters' ignorance drives the emotional response, whether it's tension or amusement.