On Service Portal, when user clicks on Profile from User menu there is no option to set Notification Preferences.
This functionality is not yet available on Service Portal. In out of the box instance there are no pages or widgets which are currently designed to provide similar functionality.
From a development standpoint, this should be an enhancement request.
Its possible to use the UI Action to determine what URL the users need to be sent to and create an 'Icon Link' widget depending on where this functionality needs to be embedded.
The UI Action is available here: