How to enable xmlrpc in WordPress 5?

What are you trying to do?

XML-RPC is enabled by default.

XML-RPC functionality is turned on by default since WordPress 3.5.

In previous versions of WordPress, XML-RPC was user enabled. To enable, go to Settings > Writing > Remote Publishing and check the checkbox.

Try going to http://example.com/wordpress/xmlrpc.php, your should see a message saying “XML-RPC server accepts POST requests only.”

Source