This code allows you to add parent term slug into single post URL

add-parent-term-slug-into-post-url.php

add_filter( 'register_post_type_args', 'je_change_post_type_rewrite_slug', 10, 2 );

/**
 * Change post type rewirte
 * Where:
 * - apartments  - is a post type slug. Replace is with your actual slug.
 * - %locations% - is a placeholder for taxonomy term in URL.
 *
 * @param  array  $args
 * @param  string $post_type_name
 * @return array
 */
function je_change_post_type_rewrite_slug( $args, $post_type_name ) {

	if ( 'apartments' !== $post_type_name ) {
		return $args;
	}

	$args['rewrite'] = array(
		'slug'       => 'apartments/%locations%',
		'with_front' => false
	);
	
	$args['has_archive'] = 'apartments';

	return $args;

}

add_filter( 'post_type_link', 'je_change_permalinks', 1, 2 );

/**
 * Change post permalink
 * Where:
 * - apartments - is a post type slug. Replace is with your actual slug.
 * - locations in wp_get_object_terms - is a taxonomy slug to get terms from. Replace it with your actual slug.
 * - %locations% - is a placeholder for term. Should be the same as in previous function.
 * - locations in second str_replace - is a default part of URL, if no terms of needed taxonomy is attached to post.
 *
 * @param  string  $post_link
 * @param  WP_Post $post
 * @return string
 */
function je_change_permalinks( $post_link, $post ) {

	if ( ! is_object( $post ) || 'apartments' !== $post->post_type ) {
		return $post_link;
	}

	$terms = wp_get_object_terms( $post->ID, 'locations' );

	if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {
		return str_replace( '%locations%' , $terms[0]->slug, $post_link );
	} else {
		return str_replace( '%locations%' , 'locations', $post_link );
	}

}

How can I make it work for hierarchical taxonomy and not just the first term (apartments/parent-category/child-category/example)

I have this gits: https://gist.github.com/liranop/118be6fa5654d07dfa76298d312e29a4