Add Google Analytics tracking code via WordPress functions.php

function add_googleanalytics() { ?>
		
	<script async src="https://www.googletagmanager.com/gtag/js?id=XX-XXXXXXXX-X"></script>
	<script>
	  window.dataLayer = window.dataLayer || [];
	  function gtag(){dataLayer.push(arguments);}
	  gtag('js', new Date());

	  gtag('config', 'XX-XXXXXXXX-X');
	</script>

<?php
}

add_action('wp_head', 'add_googleanalytics');

Thank you