Thanks Joseph for your help!
For other user, that might be interested in this topic as well:
I have included following script at the very top of the global header section of my project (see Josephs link) :
<!-- IP anonymization with gtag.js - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-xxxxxx"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag() {
dataLayer.push(arguments);
}
gtag('js', new Date());
gtag('config', 'G-xxxxxx', { 'anonymize_ip': true });
</script>
Hope that works...