You can start writing multiple OpenAPI files and merge them with tools like openapi-merger (https://www.npmjs.com/package/openapi-merger https://www.npmjs.com/p

You can start writing multiple OpenAPI files and merge them with tools like openapi-merger (https://www.npmjs.com/package/openapi-merger https://www.npmjs.com/package/openapi-merger). Is that maybe what you want?