I notice this a lot in fantasy manuscripts when I'm doing beta reads—titles either try way too hard to sound epic or they're just a character name with a colon. Both can work, but the best ones tell you the genre and the conflict. If it's 'The Something of Something' with a medieval weapon, you know it's high fantasy. If it's a single evocative word like 'Gideon' or 'Mistborn,' that works too, but only if the world itself is already famous. My own process is kinda backwards: I'll write a placeholder that's embarrassingly literal ('Guy with sword fights demon king'), then around draft two, a line of dialogue or a central metaphor usually jumps out. The title for my last project came from a throwaway bit about 'iron vows' that ended up defining the whole magic system. It’s usually hiding in the text somewhere.
For horror or thriller, shorter and punchier seems to be the rule. Something that creates an immediate, uneasy image. 'The Silent Patient' does that. 'Bird Box.' You don't need the epic prepositional phrase. Romance leans on puns, alliteration, or tropes—'The Love Hypothesis' nailed the STEM romance vibe perfectly. With literary fiction, you can get abstract or use a seemingly mundane object that holds symbolic weight. I guess the trick is to read a ton of bestseller lists in your genre and see what patterns your eye catches, then subvert them just enough to stand out.