I have quite a few ideas floating around my head but fist I would ask a few questions:

Would having the setting on another world, with magic and with sentient species other then humans while still being quite similar to one of Earth's historical ages (Ancient, Medieval and so on) be OK?

Would a setting set in some historical period (example - Victorian age) on Earth with slightly or significantly altered history at some point in past (example - Medieval age) also work?

Would a story which tells about a historical event of our history but with a different outcome (for example Great Britain crushing the American Revolutionaries) be acceptable?

Hope I get a reply soon.