How can I set anonymize_ip ?

[gibkigonzo]

I need to set anonymize_ip: true, but right now I don't have access to url that is send to GA. Even when I run ga('set', 'anonymizeIp', true); or gtag('config', '<GA_TRACKING_ID>', { 'anonymize_ip': true }); (I use gtm). How can I solve it?