получить URL с изображением
echo get_the_post_thumbnail_url();
Xenophobic Xenomorph
echo get_the_post_thumbnail_url();<?php
// ALL parameters are optional. Not needed if you are on WP LOOP
echo get_the_post_thumbnail_url( $the_query->ID, array( 500, 400) ); ?><img src='<?php the_post_thumbnail_url(); ?>'><?php if (has_post_thumbnail( $post->ID ) ): ?>
<?php $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'single-post-thumbnail' ); ?>
<div id="custom-bg" style="background-image: url('<?php echo $image[0]; ?>')">
</div>
<?php endif; ?>