get_extended()

function get_extended( $post ) {
	// Match the new style more links.
	if ( preg_match( '/<!--more(.*?)?-->/', $post, $matches ) ) {
		list($main, $extended) = explode( $matches[0], $post, 2 );
		$more_text             = $matches[1];
	} else {
		$main      = $post;
		$extended  = '';
		$more_text = '';
	}

	// Leading and trailing whitespace.
	$main      = preg_replace( '/^[s]*(.*)[s]*$/', '\1', $main );
	$extended  = preg_replace( '/^[s]*(.*)[s]*$/', '\1', $extended );
	$more_text = preg_replace( '/^[s]*(.*)[s]*$/', '\1', $more_text );

	return array(
		'main'      => $main,
		'extended'  => $extended,
		'more_text' => $more_text,
	);
}

<ul>
$post = get_post();

$myposts = get_posts( array(
	'posts_per_page' => 5
) );

foreach( $myposts as $post ) : setup_postdata( $post );  
    $content_arr = get_extended ( $post->post_content );
	?>
    <li>
       <a href="https://docs.gechiui.com/functions/get_extended/<?php the_permalink(); ?>"><?php the_title(); ?></a>
       </br>
       <?php echo $content_arr['main']; // Display the part before the more tag  ?>   
    </li>
<?php endforeach; ?>
</ul>