so not much changes in prehardmode except for a couple bosses like desert scourge (and anahita technically) but in hardmode there's aquatic scourge and i think calamitas clone at the same time as mech bosses but then you got plantera and golem like normal, i dont remember if anything comes in the middle of that but once you get to moonlord there's the stuff after him like dog and calamitas and draedon