How to change template for a standard block using layout directive action method='setTemplate'

Magento 2 (as well as Magento 1.x) supports layout directive action, which intended to run an arbitrary public method of a block (the block is an object of class \Magento\Framework\View\Element\Template or one of it descendants).
You can cnange block template by calling setTemplate method:

<referenceBlock name='copyright'>
	<action method='setTemplate'>
		<argument name='template' xsi:type='string'>Dfr_Backend::page/copyright.phtml</argument>

It works, but is regarded by the Magento core team as a legacy way.

Modern way:

<referenceBlock name='copyright'>

See also:

The “modern” way is not working now:

So use <action method='setTemplate'>