Code-Snippets-Functions/Execute a function on a child site/WooCommerce/free-shipping-on-entire-order-once-a-specific-product-is-added-to-cart.txt

add_filter( 'woocommerce_package_rates', 'hide_other_shipping_when_free_is_available', 100, 2 );
function hide_other_shipping_when_free_is_available( $rates, $package ) {
    $free = array();

    // Loop through shipping rates
    foreach ( $rates as $rate_id => $rate ) {
        // If free shipping is available
        if ( 'free_shipping' === $rate->method_id ) {
            $free[ $rate_id ] = $rate;
            break;
        }
    }
    return ! empty( $free ) ? $free : $rates;
}

add_filter( 'woocommerce_shipping_free_shipping_is_available', 'filter_free_shipping_is_available', 100, 3 );
function filter_free_shipping_is_available( $is_available, $package, $shipping_method ) {
 
    // Here set the product IDs that will enable free shipping
    $targeted_product_ids = array( 560 );

    // Loop through items for the current shipping package
    foreach ( $package['contents'] as $item ) {
        // Check if any targeted product is in cart
        if( in_array( $item['product_id'], $targeted_product_ids ) ) {
            return true;
        }
    }
    return $is_available;
}