How to change default sort order from ascending to descending in Magento 2?

In order to change default sort order from ascending to descending in Magento 2, first you need to copy vendor/magento/module-catalog/view/frontend/layout/catalog_category_view.xml to app/design/frontend/{{Vender_Namespace}}/{{Theme_Name}}/Magento_Catalog/layout/catalog_category_view.xml into your theme.

Now copy below code to your new xml file.

Thats it. Enjoy Magento 2!! Enjoy Magewallet!!!

Ref: http://magento.stackexchange.com/questions/119642/magento2-default-to-sort-by-price-descending-not-ascending