Multi reference - a basic question

I’m not sure what you want to achieve, but if you want to get the IDs of all the references in a field.
To somethink like that:

// Get Multi-Item Reference ID
async function getReferenceID(database, referenceField) {
 const res = await wixData.query(database)
        .include(referenceField)
        .find();
 return  res.items.map(e => e._id );
}