WordPress at a glance
function is not described

get_tag_feed_link() WP 2.3.0

Retrieves the permalink for a tag feed.

No Hooks.

Return

String. The feed permalink for the given tag.

Usage

get_tag_feed_link( $tag_id, $feed );
$tag_id(int) (required)
Tag ID.
$feed(string)
Feed type.
Default: ''

Code of get tag feed link: wp-includes/link-template.php WP 5.2.2

<?php
function get_tag_feed_link( $tag_id, $feed = '' ) {
	return get_term_feed_link( $tag_id, 'post_tag', $feed );
}