How to add tag in bulk from Contacts Page
Go to CRM then Click「Contacts」，go to the Contacts page
Hover on one contact, then you'll find a check box, click it
After selecting the contacts, click [Bulk Actions] at the top right and select [Add Tag]
Then you can search for a tag from the tag list or type to create a new tag, click [Save] after done.
Another method is you can add tags in bulk with a CSV file, please refer to: 👇🏻