Yes it works fine with new tracking ID's. I have checked the latest Javascript code install instructions from Google, and it's the same as X3 is already using. You just need to insert your tracking ID, no matter how the code is formatted.
This is the code noted by Google and used internally by X3:
<script async src="https://www.googletagmanager.com/gtag/js?id=TRACKINGID"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'TRACKINGID');
</script>
If it wasn't working (for any reason), you could just leave the "Google Analytics" input field empty, and instead just copy-paste the full Javascript, as instructed from your Google Analytics account, directly into X3 Settings > Custom > <head>.