the “echo and get” solution is normally a “not in loop” solution. Unfortunatelly, outside a loop (so, in our case), if your not having a “created user excerpt” get_the_excerpt is empty. If you just want a “cut” content to make an excerpt you can use this :
<?php
$content_post = get_post($query_id);
$content = $content_post->post_content;
$excerpt = wp_trim_words( $content , 20, '...');
echo $excerpt;
?>
Where “20” is the char’ length of the excerpt you want, and “…” the text after the excerpt if the content was cut.
