Surrond h1 entry-title automatically with a span tag

You could either add the span in your template file like this:

<h1><span><?php the_title() ?></span></h1>

Or you could add a filter to manipulate the output like this:

add_filter('the_title', function ($title) {
  $title="<span>" . $title . '</span>';
  return $title;
});