How to add a title text input to an image field node form widget
You have to enable the title field on your image field in the manage field tabs, at the bottom of the field form. for example at
example.comadmin/structure/types/manage/example_content_type/fields/node.example_content_type.field_example_field

Found the answer after landing here: https://www.drupal.org/project/drupal/issues/2303765