Linked Wearables are a way to represent NFTs as Wearables in Decentraland. Third parties need to submit a proposal to be approved by the DAO in order to access the tool in the Builder and get slots to submit the 3D models. By using this tool, you will be able to submit NFTs as Wearables to be curated and made available for your NFT holders inside Decentraland.
Note that after being approved, you will need to create an API with the endpoints described in the ADR-42 third-party assets integration document.