You can find a vault and steal the slab and command the demon, which leaves a goblins civ leaderless, or take possession of some of the worlds greatest artifacts, and make sure everyone knows about it. Adventurers searching for those artifacts will seek you out, and your possession of them will be remembered.
There is also one trick that can make your adventurer king of a dwarven civ; first it must be the only site-playable civ in the world, and it must have died and have no remaining members (you can't play as a dead civ if there are still surviving playable civs). Then you need to make and retire a fort, with a pop cap of less than 7, before the caravan arrives (because caravan merchants become historical figures who can inherit positions) with one militia commander. Find that commander in adventure mode, having killed a couple beasts or something, and convince him to make you a soldier of the fort. Now wait until Autumn has passed (so a caravan doesn't arrive!), and unretire that fort. Your adventurer should be a member of the fort now. Stuff everyone else in like a room with a drawbridge and smash them. With your adventurer as the sole surviving member of the civ, they should be named king eventually. Then abandon the fort and unretire your royal adventurer.
Only issue I had with it was that sometimes the game will make you king, then decide the civ also needs a general, and immediately make your adventurer general instead. So I got several adventurers to join the fort before unretiring and each of them would get a different title, eventually.
You can force the world to only have one playable civ by going into the raws and duplicating the MOUNTAIN entity and naming the duplicate MOUNTAIN_UNPLAYABLE or something, and removing the site_controllable tag from it. Then go back to the original MOUNTAIN civ, keep it's playable tag, but remove it's settlement biome tags, remove all the likes_site and tolerates_site tags besides cave_detailed, and change the max civ number to 1. Now every world will have only a single playable civ, and because they can't make new settlements and won't conquer new sites, they will be restricted to the founding fort, which is vulnerable to all sorts of horrible ways to be wiped out. But, other dwarven civs you can't play as still exist so the world isn't without dwarves, because of the duplicate, unplayable entity.