blog-posting-from-microsoft-word

So one way you can handle this issue is by making the very first image the featured image by putting the following code in your functions.php file on your child theme.

function wpsites_auto_set_featured_image() {
global $post;
$featured_image_exists = has_post_thumbnail($post->ID);
if (!$featured_image_exists) {
$attached_image = get_children( "post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );
if ($attached_image) {
foreach ($attached_image as $attachment_id => $attachment) {
set_post_thumbnail($post->ID, $attachment_id);
}
}
}
}
add_action('the_post', 'wpsites_auto_set_featured_image');