How To Get Tag ID by Tag Name, (and) Tag ID Directly On Tag Pages

If you want to get Tag ID, when you already have the Tag Name, following code snippet can be used.

$tag = get_term_by ( 'name', single_tag_title( '', false ), 'post_tag' );
$tag_id = $tag->term_id;

If you don’t have the Tag Name already, this code can be used.

$tag_id = get_queried_object()->term_id;

I have tested both codes on Tag Archive pages.