Can I create Tagging Rules based on activity frequency?

Yes. Tagging Rules can be created based on Activity frequency – the number of times some activity is performed.
Go to the Settings tab by clicking on the gear icon located on the top right corner.
On the left pane, click on Tagging Rules.
Click on Add New Rule button on the top right corner.
Select Based on activity option in the popup that opens.
Choose the appropriate activity condition.
Select the count. Count is the frequency of the activity that should be performed by the contact before the tag is assigned to that contact.
Select the Tag that you want to assign to contacts that satisfy the selected activity condition.
Click on Add.