get-children-products.php

<?php

function getChildrenProducts()
{
    $productId   = get_the_ID();
    $product     = wc_get_product($productId);
    $childrenIds = $product->get_children();

    if (empty($childrenIds)) {
        return [];
    }

    $children = wc_get_products([
        'include' => $childrenIds,
    ]);

    if (empty($children)) {
        return [];
    }

    return $children;
}