A form can be automatically emailed upon form submission through Form Actions. 

You can manually send a PDF through the Web Portal > Forms > Submitted Forms > Select the Form you want to send as a PDF > Select View PDF > Email PDF > Select the Contact and fill in details > Send Email. 

This can also be done through a form in the Activity section of the contact card. Web Portal > CRM > Contacts > Select the contact >  Activity > Forms > PDF > EMAIL PDF. 

On the App > Forms > Submitted Forms > Swipe Left > Email.