Non-Modified But Relevant Command:

/newisland (when you get an island from when you begin the game) will give you the starter island that we have now.

Modified Command:

/newisland replace will keep all items in your inventory and spawn you onto a piece of bedrock instead of the islands we have now.

This way you can keep all items from previous island and making it impossible* to island farm.

*Unless if you get kicked from a coop so you have no island. That means you can't do /newisland replace , instead you have to do /newisland so you will get the starter island.

Let's see what you think...