Originally posted by logarou -=bzh=-:

Otherwise there is this MOD to have a supercontinent, in one piece, it brings together all the biomes, large exploration for adventurers at heart! https://www.nexusmods.com/valheim/mods/616

That mod requires Better Continents which by itself lets you have a large continent pretty easily. It worked for me on default settings, but that could just be coincidence with my seed.