@dayaftergroup it is nice if you provide users all kind of details to manage their privacy!
However, with the GDPR you should put into the policies how to refuse/manage the cookies (from the browser) and the links to the policies of the used third party services.
@michacassola to be honest I do not know how other software manages cookie.
It is possible to delete the cookies saved from third party services and related for the specific domain (in the previous comment I was talking about cookie saved from third party services but related to their domains, not your domain) but there are 2 considerations:
1) If I delete the cookies, there is a possibility to interfere with some features of the third party service (or broke something);
2) Avoiding that the service starts, those cookies are irrelevant even if they are present.
Maybe I did not understand:
In the inspector in the application-cookies settings only my domain shows up for cookies, although I use GTM
in which scenario?