First, is it even possible to change the page title from a plugin (specifically, from a shortcode defined in a plugin)? This answer says no, but there are certainly reasonable use cases for it. Like, say, my use case (the shortcode displays detail page content for an item of a collection … so, I put the shortcode on a page; what’s the page title supposed to be? It depends on the detail item.).

I have tried every method I can find:

$_SESSION['custom_page_title'] = $eventData['eventtitle'];


//attempt 1
add_filter('document_title_parts', 'my_custom_title');
function my_custom_title( $title ) {
  // $title is an array of title parts, including one called `title`

  $title['title'] = stripslashes($_SESSION['custom_page_title']);

  return $title;
}


//attempt 2
add_filter("pre_get_document_title", "my_callback");
function my_callback($old_title){
    return stripslashes($_SESSION['custom_page_title']);
}


//attempt 3
add_filter('the_title','some_callback');
function some_callback($data){
    return stripslashes($_SESSION['custom_page_title']);

}


//attempt 4
add_filter( 'wp_title', 'custom_titles', 10, 2 );
function custom_titles( $title, $sep ) {

    //Check if custom titles are enabled from your option framework
    if ( ot_get_option( 'enable_custom_titles' ) === 'on' ||  (1 == 1)) {
        $title = stripslashes($_SESSION['custom_page_title']);
    }

    return $title;
}

But none of them work (with default twentytwentyone theme).

Is it possible, and if so, how?