I get zero empathy from fiction. Never think "Oh, this guy I met must feel like Atticus Finch" or "So sad, it's like The Grapes of Wrath." I get empathy from reading real people on Reddit saying "you know what's tough about being a waiter/chemist/influencer?" because they explain how real people think.
Empathy may not be the right term for this, but I've noticed recently times of emotional resonance with some characters/stories. One recent example that I particularly noticed this with was actually a Harry Potter fan fiction. It was fairly well written, but you know, not exactly fine literature. But I noticed how activated my emotions were getting reading those stories, the anger coming up about how the character was being treated, the sense of righteousness in her response to the circumstances and people around her.
I'm not sure if that helped me understand other people better, but I think it may have helped me understand myself a little better. Get a little more in touch with my emotions about parts of my own life. A little catharsis.
And this is not the point, but I think that getting in touch with my own feelings more probably does lead to more empathy for me. I've definitely noticed that when I feel more compassion for myself, I often also notice an increased sense of compassion for others who I perceive similarly.
I assume anything I read on reddit at this point is AI written click bait, so giant grains of salt on any personal anecdote probably gives me the opposite reaction.
A mother cat teaches her kittens to hunt by demonstrating it on a dead mouse. Fiction works the same way: by showing it on a dummy. In real life things are small and overlapped. Fiction makes them big and separate. Once you've seen it big and separate, you can recognize it small and overlapped.