You could always look into playing with mods. There are some really great content mods, such as Thorium, Calamity, Spirit and Tremor, which add a lot of new content in the form of new mobs, weapons, armor, items, bosses, and even biomes, often with an emphasis on new post-Moonlord content. The one downside (if you can call it such, I saw it as a great motivating factor to play more) is that you have to start from scratch with a new world. (Actually, now that I think about it, there shouldn't be any technical reason you couldn't copy any vanilla characters, with all their gear and items, into the mods-only player folder to have continued access to them when playing with mods (though this does essentially "fork" the character)).