Based on my own experience
Low-Magic Fantasy fiction
Ideas for stories always start in my head as the mundane type. An everyday-life story that showcases a sensitivity to feelings and life in general. But the thing is, I choose to set it in an entirely ANOTHER WORLD.
So basically, it’s a mundane life in another world. And that’s the hardest thing, in order to make everything sound natural and non-extravagant, the world must be pre-existing in the story. It has existed thousands of years even before the start of the story I’m making. Details will have to be consistent and coherent.
And from there I build. There will be action. Romance. Thrill. But everything is grounded on a pre-built world that the character does NOT have to unfold.
And the most convincing thing about this, you DON’T NEED so much RESEARCH. No interviews. Not much googling. You only need your day-to-day experience. Change details consistently and you have a story. A story you can finish as long as the WORLD YOU BUILT IS COMPLETE.
It doesn't have to have castles or dragons or any magic at all. Although a little magic always adds a mystery. Just a little. Don't overuse it.
Just take for example, ADVENTURE TIME where the main elements are fire, ice, candy and slime. And GOT where they have their own gods. And STUDIO GHIBLI that takes you to wonders.
And one last thing, you can put mysteries that you don’t need to clarify. Because if your character who lives there doesn’t know it, why would anybody else know it?
Hope I helped.