add_filter( 'aioseo_schema_output', function ( $schema ) {

    foreach ( $schema as &$schemaItem ) {

        if ( isset( $schemaItem['@type'] ) && 'Product' === $schemaItem['@type'] ) {

			if(!empty($schemaItem["offers"]["shippingDetails"])){

				// Loop inside the Offers > shippingDetails schema

				foreach( $schemaItem["offers"]["shippingDetails"] as &$schemaItemChild ){

				// Check for OfferShippingDetails schema where we need to add the deliveryTime schema

				if( isset( $schemaItemChild['@type'] ) && 'OfferShippingDetails' === $schemaItemChild['@type'] ){

					// Adding the deliveryTime schema

					$schemaItemChild["deliveryTime"] = [

						"@type" => "ShippingDeliveryTime",

						"handlingTime" => [

							"@type" => "QuantitativeValue",

							"minValue" => 1,

							"maxValue" => 2,

							"unitCode" => "d"

						],

						"transitTime" => [

							"@type" => "QuantitativeValue",

							"minValue" => 1,

							"maxValue" => 3,

							"unitCode" => "d"

						]

					];

				}

			}		

			}	

        }

    }

    return $schema;

}, 10, 2 );