If you have a collection that references another collection, and you want one query to retrieve data from both, use the .include() extension.
Here we have a Cars collection which references the Manufacturers collection using the 'make' field.
Use the name of the referencing field in a `.include()` in your query, and you get both collections returned in your results.
wixData.query("Cars")
.include("make")
.find()
.then((results) => {
console.log(JSON.stringify(results.items));
});