Code snippet to Add extra costs based on box sizes using WooCommerce UPS Shipping Plugin: https://www.pluginhive.com/product/woocommerce-ups-shipping-plugin-with-print-label/

gistfile1.txt

add_filter('wf_ups_rate', 'wf_modify_ups_rate', 10, 2);
function wf_modify_ups_rate($xml, $packages){
  //Config this array with box dimensions and rate to be added.
  $extra_coast  = array(
			'7,9,8' => 10,
      '10,6,8' => 15,
		); 
	
	if($xml){
		foreach ($extra_coast as $extra_coast_dim => $amount_to_add) {
			$dimension_arrey = explode(",",$extra_coast_dim);
			foreach ($packages as $i => $package) {
				if( compare_package_dimensions($package['Package']['Dimensions'], $dimension_arrey) ){
					//if negotiated rate
					if( isset($xml->RatedShipment->NegotiatedRates->NetSummaryCharges->GrandTotal->MonetaryValue) ){
						if( property_exists($xml->RatedShipment->NegotiatedRates->NetSummaryCharges, 'TotalChargesWithTaxes') ){
							$xml->RatedShipment->NegotiatedRates->NetSummaryCharges->TotalChargesWithTaxes->MonetaryValue += $amount_to_add;
						}else{
							$xml->RatedShipment->NegotiatedRates->NetSummaryCharges->GrandTotal->MonetaryValue += $amount_to_add;
						}
					}

					// if normal rate
					$xml->RatedShipment->TotalCharges->MonetaryValue += $amount_to_add;
				}
			}
		}
	}
	return $xml;
}
function compare_package_dimensions($package, $dimension_arrey){
	foreach ($dimension_arrey as $key => &$value) {
		if( isset($package['Length']) && $value == $package['Length']  ){
			unset($package['Length']);
		}elseif( isset($package['Width']) && $value == $package['Width']  ){
			unset($package['Width']);
		}elseif( isset($package['Height']) && $value == $package['Height']  ){
			unset($package['Height']);
		}
	}
	if( empty($package['Length']) && empty($package['Width']) && empty($package['Height']) ){
		return true;
	}
	return false;
}