Creating Dynamic Order Status Changes in WooCommerce

dynamic-order-status-woocommerce.php

<?php
/**
 * Change order status to Extras Only if all ordered items from Extras category 
 * Change order status to Proc/ Gift Box if product addon gif box selected YES
 * Change order status to Intl Order if order is not from US/Canada 
 */
function change_status_giftbox_and_extrasonly( $order_id ) {
    if ( ! $order_id ) return;

    // Get order object
    $order = wc_get_order( $order_id );

    // Ensure the order is 'processing'
    if ($order->get_status() !== 'processing') return;

    // Specific categories: the term name/term_id/slug. Several could be added, separated by a comma
    $categories = array( 'extras' );
    
    // Flag
    $found = true;
    $gift_found = false;
    $country = "";

    // grab country name
    if ($order->get_shipping_country() == "US" OR $order->get_shipping_country() == "Canada" OR $order->get_shipping_country() == "CA" OR $order->get_billing_country() == "US" OR $order->get_billing_country() == "Canada" OR $order->get_billing_country() == "CA") {
        // printf( esc_html__( 'Non-international Order.', 'woocommerce' ) );
        $country = "domestic";

    }else {
        $country = "international";
    }
    
    // Loop through order items
    foreach ( $order->get_items() as $item ) {

        // PROC/GIFT BOX STATUS
        // Here, we can get the value by a specific metakey
        if ( $item->get_meta( "_Gift Ready Milk Collection Kit" ) ) {
            // Test if string contains the word 
            if(strpos($item->get_meta( "_Gift Ready Milk Collection Kit" ), "No") === false){
                $found = false;
                $gift_found = true;
                break;
            }
        }

        // EXTRAS ONLY STATUS
        // Product ID
        $product_id = $item->get_variation_id() > 0 ? $item->get_variation_id() : $item->get_product_id();

        // Has term (product category)
        if ( !has_term( $categories, 'product_cat', $product_id ) ) {
            $found = false;
        }
    }
    
    // without wc- prefix, change order status
    if ( $found ) {
        $order->update_status( 'extras' );
    }elseif ( $gift_found ) {
        $order->update_status( 'process-gift-box' );
    }elseif ( !$found && !$gift_found && $country == "international" ) {
        $order->update_status( 'intl-order' );
    }
}
add_action( 'woocommerce_thankyou', 'change_status_giftbox_and_extrasonly', 10, 1 );

You can find the code explanation on this article Creating Dynamic Order Status Changes in WooCommerce: An In-Depth Guide