Conditional logic is available to Dropbox Sign users on a Premium plan.
Conditional logic allows you to create rules, or conditions, that change which fields appear on a document based on input from a signer. For example, you could use conditional logic to set up your document so that if a signer checks a checkbox, a dropdown field will appear. You can add conditional logic to signature requests and templates.
Before you create a conditional logic rule, you’ll need to choose a trigger field and selected fields. The trigger field, when completed by the signer, will trigger the selected fields to appear or remain hidden. In the example above, the checkbox is the trigger field and the dropdown is the selected field.