excerpt-tags.php

<?php
/**
 * Plugin Name: Add post tags to the excerpt.
 * Plugin URI: https://prothemedesign.com
 * Description: Add post tags to the excerpt.
 * Author: Ben Gillbanks
 * Version: 1.0
 * Author URI: https://prothemedesign.com
 * Text Domain: ptd
 */

/**
 * Add post tags to the end of the excerpt.
 *
 * @param string $excerpt The post excerpt.
 * @return string
 */
function ptd_excerpt_tags( $excerpt ) {

	$tags = get_the_tags();
	$html = '';

	// Display tags (if there are any).
	if ( $tags ) {
		foreach( $tags as $tag ) {
			$html .= sprintf(
				'<a href="%1$s">%2$s</a>',
				esc_url( $tag->name ),
				esc_html( $tag->name )
			);
		}
	}

	if ( $html ) {
		$html = '<span class="post-tags">' . $html . '</span>';
	}

	return $excerpt . $html;

}

add_filter( 'get_the_excerpt', 'ptd_excerpt_tags' );


/**
 * Display post tags styles.
 *
 * @return void
 */
function ptd_excerpt_tags_styles() {
?>
<style>
	.post-tags {
		display: block;
		font-size: 0.7rem;
		margin-top: 8px;
	}
	.post-tags a {
		padding: 0.1em 0.4em;
		background: #eee;
		display: inline-block;
		margin-inline-end: 0.25em;
	}
</style>
<?php

}

add_action( 'wp_head', 'ptd_excerpt_tags_styles' );