How can I link E-Mail greetings/Postal greetings to "formal" or "informal" communication style?

is there a way to link a defined E-Mail greeting or Postal greeting if the communication style "formal" or "informal" is selected?

I thought it could work with CiviRules but we don’t have it installed so far. So is there another way? I already tried it with the following token:

{if"{contact.communication_style}=="formell"}Sehr geehrte Damen und Herren

But it doesn’t work. If I select "formell" there is still another greeting selected.

Thank you for any help
Tina