Event Check In
For physical, IRL events, you can create a form that lets registrants check-in at your event.
Open the Finder and right-click on the folder that contains your event. Create your form in this folder.
Add an Event Check-In element to you new form.
Go to Form Actions and configure its settings:
Event Check-In Action

The Event Check-In element also allows prospects to register and check-in simultaneously.
tip
Publish your check-in form on a dedicated Landing Page.
Generate a QR code (via free 3rd party tools) that points to this page.
Registrants can scan the QR code and check themselves in via the phones.