Show featured image full width before the content area

The code will be added to wp-content/themes/kleo-child/functions.php

add_action( 'kleo_before_main', 'sq7rdu_show_featured_before_content' );
function sq7rdu_show_featured_before_content() {
  if ( is_single() && has_post_thumbnail() ) {
    echo '';
    the_post_thumbnail( 'full' );
    echo '';
  }
}

Below is a screenshot with an example of the function usage.