Create single.php for specific tag by tag id or name

Question

has_tag() is a function that will check if a post has a certain tag

You could integrate it into your code like so:

function my_category_templates($single_template) {
 global $post;

 if ( in_category( 'raspee' )) {
    $single_template = dirname( __FILE__ ) . '/single-raspee.php';
 }

 if ( has_tag( 'everyone' )) {
    $single_template = dirname( __FILE__ ) . '/single-everyone.php';
 }

  return $single_template;
 }
 add_filter( "single_template", "my_category_templates" );

you can check out this function here:
https://developer.wordpress.org/reference/functions/has_tag/