$terms = get_terms(\'CUSTOM_TAXONOMY\', [\'hide_empty\' => true]);
foreach( $terms as $term ){
    echo \'<section>\';
    echo \'<h1>\' . $term->name . \'</h1>\';

    $posts = get_posts([
        \'post_type\' => \'CUSTOM_POST_TYPE\'
        \'tax_query\' => [
            [
                \'taxonomy\'  => \'CUSTOM_TAXONOMY\',
                \'field\'     => \'term_id\',
                \'terms\'     => $term->term_id
            ]
        ]   
    ]);

    echo \'<ul>\';
    foreach($posts as $post){
            echo sprintf(\'<li><a href="%s">%s</a></li>\', get_permalink($post), $post->post_title);
    }
    echo \'</ul>\';
    echo \'</section>\';
}