Flexible Content Sync for ACF copies one post or page, with all of its content and every ACF field value, from one WordPress site to another. Export downloads a single JSON file; import reads that file and creates a brand new draft post with everything rebuilt — including images, repeaters, flexible content, relationships, and taxonomy terms.
Requires Advanced Custom Fields (or ACF PRO) to be installed and active. Core post fields (title, content, excerpt, featured image, taxonomies) still export/import without ACF, but ACF field values will not.