That depends on how comfortable you are with JavaScript and AJAX.
I have an example that does almost exactly what you’re looking for. It populates a text field, a textarea field and an image field based on a selection in a relationship field. You would actually be creating a simplified version of it because you’re populating all text based fields. You can find my example here https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-fields-on-relationship
