If you want an account not linked to your identity to sign up for accounts also not linked to your identity. To create spam, fake or throw away accounts on other services, any email provider will do. Some do a form of KYC, but it’s lackluster in most cases. Popular providers for “normal people” like Yahoo, Gmail and Outlook are great, when you want to keep a low profile registering for services with your “anonymous“ email address.
Of course you have to sign up and sign in using an VPN or Tor.
Please don’t do illegal stuff and especially don’t bring harm to others.