Add Different Base Fee to Shipping Option

base-fees-table-rate-shipping.php

add_filter( 'woocommerce_package_rates', 'add_shipping_option_base_fee', 10, 2 );
function add_shipping_option_base_fee( $rates, $package ) {

    foreach( $rates as $key => $rate ) {
        // reset defaults
        $highest_priority = $highest_class = 0;

        // Do not apply base fee if not the right option
        if( $rate->id !== 'betrs_shipping:1-1' ) continue;

        // find highest priority class (BE Table Rate Shipping Only)
        foreach( $package['contents'] as $key => $values ) {
            $shipping_class = $values[ 'data' ]->get_shipping_class();
            $get_priority = get_term_meta( $shipping_class->get_id(), 'priority', true );
            if( $get_priority > $highest_priority ) {
                $highest_priority = $get_priority;
                $highest_class = $shipping_class->get_id();
            }
        }

        switch( $highest_class ) {
            case 'ornaments':
                $rates[ $key ]->cost += 4.00;
                break;
            case 'cake-toppers':
                $rates[ $key ]->cost += 5.00;
                break;
            case 'cutting-boards':
            default:
                $rates[ $key ]->cost += 0.00;
                break;
        }
    }
   
    return $rates;
}