Query from portfolio with related categories

// Initialize an array to store random IDs per category
$random_ids_per_category = array();

// Loop through the related categories
foreach ($related_categories as $category) {
// Perform a query to get the related IDs for the current category
$query = new WP_Query(
array(
'post_type' => 'portfolio',
'posts_per_page' => -1,
'tax_query' => array(
array(
'taxonomy' => 'taxonomy_name', // Replace 'taxonomy_name' with the name of your taxonomy
'field' => 'term_id',
'terms' => $category->term_id,
),
),
'fields' => 'ids', // Get only the post IDs
)
);

// Get the post IDs found
$post_ids = $query->posts;

// Select a random post ID from the found IDs
$random_post_id = $post_ids[array_rand($post_ids)];

// Store the random ID per category
$random_ids_per_category[$category->term_id] = $random_post_id;
}

// Now, $random_ids_per_category contains a random ID per category

$related_portfolio = new WP_Query(
array(
'post_type' => 'portfolio',
'posts_per_page' => 4,
'post__in' => $random_ids_per_category,
'orderby' => 'post__in',
)
);