Unlike many modern titles, the first Dragon Quest Builders on Switch doesn't have traditional paid DLC. Instead, it includes for its free-build mode, Terra Incognita :
You can ride this monster to travel faster and gain specialized materials. Dragon Quest Builders Switch NSP DLCs
The largest pack, offering over 70 recipes for modern luxury structures, like glass walls, trendy furniture, and new hairstyles. Which One is for You? Unlike many modern titles, the first Dragon Quest
Adds a new fishing island, a fishing rod tool, and dozens of fish species to catch and display in aquariums. Unlike many modern titles
If you're seeing "NSP" files or DLC listings, they likely refer to the sequel, which features several major expansion packs: