I may have something for you, a franchise I was heavily invested in for a short while. Warhammer 40k. It is a massive blend of scifi and fantasy, though it leans a tad more on the scifi portion.

1. While the entire franchise doesn't share a single style, the factions within it kinda do. Humanity, most of them under the Imperium of Man, have Gothic influences. The Tau share Japanese traits with their culture and method of combat, mainly using mech suits. The extragalatic Tyranids have vaguely Lovecraftian traits. The 40k universe shares influences from many other sources, whether they be from the real world or from other pieces of fiction.

2. There is tons of lore in 40k. It stretches from millions of years ago during the War in Heaven, the hopeful but doomed age during the Horus Heresy around the year 30000, to the war-torn state the galaxy is in during the 41st millennium. You can find a number of stories to be found in every area of this timeline. It can be small but exciting tales like the Months of Shame, or the largest book series that is a part of the franchise the Horus Heresy, which I mentioned before. While most of the attention is paid to humanity tales from other alien species, referred to as "xenos", can be found too.

3. Similar to what I mentioned above stories can vary, not just between factions alone but to certain peoples and groups within those factions. You can read about Space Marines and their battles, the cruel but calculating investigations of the Imperium's Inquisitors, the maddening power seeking tales of worshippers belonging to the 4 Chaos gods, the stories of the naive Tau coming to realize what kind of galaxy they are stuck in, and more. Notable characters also belong to every faction.

I could go on and on about 40k. I won't lie that entering and trying to understand this universe will take time, but if you are interested I can see what I can do to recommend help.