WordPress link to page

Link to page by url slug (alias). Does not work with subpages:

<?php
echo get_permalink( get_page_by_path( 'map' ) );
?>

Link to page by title:

<?php
echo get_permalink( get_page_by_title( 'Map' ) );
?>

Link to page relative from homepage:

<?php
echo home_url( '/map/' );
?>

Link to page by slug (alias). Works with subpages:

<?php
function get_permalink_by_slug( $slug ) {
    
    $permalink = null; // Initialize the permalink value
    
    $args = array( // Build the arguments for WP_Query
        'name' => $slug,
        'posts_per_page' => 1,
        'post_type' => 'page'
    );

    // Run the query (and reset it)
    $query = new WP_Query( $args );
    if( $query->have_posts() ) {
        $query->the_post();
        $permalink = get_permalink( get_the_ID() );
    }
    wp_reset_postdata();

    return $permalink;
}


echo get_permalink_by_slug('contact-us');
?>