Boss Chests Contain Legendaries Mod

If you'd prefer to get your legendaries the old-fashioned way (i.e. extricating them from the dismembered corpses of your slain foes) but still want to get more of them, check out Custom Legendary Enemy Spawning by Iron Rose, which I personally use alongside this mod.

Obviously this mod doesn't include the Steamer Trunks you can build at workshop settlements since that would be ridiculous (although it wouldn't be a bad idea for another mod; spend a bunch of resources for a random legendary).