One of the big debates in writing fiction is plotting versus pantsing. Outlining your story ahead of time, or making it up as you go along.
Personally, I like having an outline and knowing where I’m heading in a story. But at the same time, I understand the preference to write from the seat of your pants because if you become too adherent to an outline, you may start forcing your characters to move from plot point to plot point, rather than seriously thinking about what the character would say or do in that situation. A writer should always be thinking, “If this was a real person, how would they actually react?” That’s the key to creating a believable and emotionally engaging story—real characters, not plot props.
What works best for me is to start with an outline, but if I find that one of my characters wants to take the story in a different direction than I originally planned, I let them. I can always go back and rewrite.