You can’t edit “templates” in the traditional way when using elementor. Your choices are limited. You can get elementor pro and you can create templates. You can include fields using elementor pro widgets using it’s ACF integration. You can create filters in WP to add content to like the excerpt. You can build your own shortcodes. Nothing short of creating custom code will add custom fields to the excerpt in elementor.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users