Sadly do not know much about Google Tag Manager. But pretty sure it runs some kind of JavaScript. n8n is then for sure the wrong tool for that. If you want that JavaScript gets executed you have to call it with a headless browser.
You could try this community node:
Is however more complex to install to a regular node as it has other dependencies. You can find some more information about that here:
If actually all you care about is to show up in Google Analytics you can check in your browser what kind of request gets made by that JavaScript code and do exactly the same.