It’s not possible to turn off notifications of assignment for those that were generated automatically (by a filter).
You can turn them off for all causes of assignment, but I suspect that’s not what you need.
I realise that I may have misunderstood your question. Are you asking about notifications that come from a rule that assigns a user, or notifications that come because a user is automatically assigned due to the creation of a card in a view with a filter of ‘Assigned to me’.
I was answering about the latter, but if you meant the former, then it is possible to turn off notifications generated by rules: