add_action( 'pre_get_posts', 'custom_woocommerce_products_per_page' );

function custom_woocommerce_products_per_page( $query ) {
    // Check if we're on a WooCommerce shop page or product category or tag page and if it's the main query
    if( !is_admin() && $query->is_main_query() && (is_woocommerce() || is_product_category() || is_product_tag()) ) {
        $query->set( 'posts_per_page', 9 ); // Set the number of products per page to 12
    }
}