Easy Achievement with the console command: GetPlayer().profile:UnlockEverything()
This command will unlock all the characters.
Players can open a console menu by pressing ~ ( English/French), ^ or ö (German Keyboard Layout) æ or ø (Scandinavian Keyboard) or ù (Azerty Keyboard Layout) and "Ñ" in the Spanish Keyboard. It can be hid again by pressing Ctrl + L.
U have all the commands here.
https://dontstarve.fandom.com/wiki/Console/Commands