Load specific ACF Flexible Content fields for new Posts

ACF-load-flex-fields-new-posts.php

// "flexible_content" below, is the name of the Flexible Content field
add_filter('acf/load_value/name=flexible_content', 'add_fields', 10, 3); 

  function  add_fields($value, $post_id, $field) {
    if ($value !== NULL) {  // $value will only be empty for New Posts
      return $value;
    }
    // lead layouts
    $value = array(
      array(
        'acf_fc_layout' => 'heading'  // heading is the name of the layout
      ),
      array(
        'acf_fc_layout' => 'wysiwyg_editor' // wysiwyg_editor is the name of the layout
      )
    );
    return $value;
  }