Afterwards ... but I usually have a rough idea of what I want to happen in the story.
Found family is typically there because I believe we build our families through shared experiences (& we need them). Enemies to lovers often crops up in my stories because not all loves begin with a sweet "meet cute" and wind up HEA... The one story I've written where they experience love at first sight, he breaks her heart and they become enemies for quite a while before reconnecting.
But I don't plan my writing around the tropes, but at least SOME tropes happen anyway in most books, like "chosen one", orphans, tortured heroes, quests, dark lords, portal / "fish out of water", lost heir, mentor's sacrifice (Gandalf's "Fly, you fools!"), red herrings, reversal of fortune, betrayals, cliffhangers, etc.