Remember: Always dump your own games and DLC if you own them legally. This article is for educational purposes regarding file formats and preservation.
Official DLC can be purchased through the Nintendo eShop. Simply navigate to the game's page, and if there's DLC available, you'll see an option to purchase it. Dragon Quest Builders SWITCH NSP -DLC-
As you build, monsters will attack. Use traps and high walls early on to protect your hard work. Remember: Always dump your own games and DLC