Want to test the Magento 2 success page after making some changes there without placing many orders in your Magento 2 store? By changing the following code in vendor/magento/module-checkout/Controller/Onepage/Success.php you only have to place one order. So look for the following line of code and simply comment it out:
$session->clearQuote(); // before
//$session->clearQuote(); // after
You can now reload the page as often as you like. Make sure to undo your changes when you are done!