Hey there,

please give the pinned FAQ post a look:
https://steamcommunity.com/app/892970/discussions/0/3383905288030494726/

Also, you can explore new content / new maps with your existing character and bring new items back to your old world in your inventory. Recipe unlocks are tied to your character and have so far come over seamlessly to old worlds. IGS doesn't give any guarantees that legacy worlds will stay compatible with future updates, but so far it's looking good.

Have a good day!