What if two civilizations were fundamentally incompatible and the only recourse was war? The Sun Eater series by Christopher Ruocchio is a good read if you have some tolerance for melodrama and minor pacing issues. It's thousands of years in the future and humans are living on thousands of different planets. The technology is hard to distinguish from magic but the social structure is late stage Roman Empire. Roucchio uses a first-person narrative framing device to great effect. Think Kvothe in The Name of the Wind. And just like Kvothe the protagonist (Hadrian Marlowe) is a bit self-absorbed. But unlike Kvothe it's established in the first paragraph that Hadrian will follow an "innocent Anakin becomes jaded Vader" arc. The world-building is strong, too. There's echoes of Dune, The Hunger Games, Red Rising, and Game of Thrones, but the storytelling doesn't usually feel derivative. The killer combo for me is that Ruocchio is unsentimental about politics and power but optimistic about what groups of individuals can do. I had never seen a speculative fiction writer explicitly reference Jouvenel's high-low vs middle dynamic. And yes there's an alien civilization but first contact is less Arrival and more "let's be friends oh wait you seem to enjoy the taste of human flesh as something of a delicacy."