<?php
/**
 * Get add-ons meta data from the order
 */
function prefix_order_data( $order_id ) {
	$order = wc_get_order( $order_id );
	$order_line_items = $order->get_items();
	foreach( $order_line_items as $line_item ) {
		// This is your add-ons data for each line item
		$addons_data = $line_item->get_meta( 'product_extras' );
	}
}