Sourcing Auto Complete from External system of record

We have a requirement, where the auto complete should get the API results dynamically, based on the text inputted by user in the auto complete field. With the data reference configuration suggested in Source a dropdown from external system of record | Support Center, we are unable to achieve our requirement, as the value input in auto complete field is not re-triggering the Dpage and API call. Could someone please guide on this. Thanks.