{!$Context.ContactId} and {!$Context.RoutableId} should be used to display the Context Variables ContactId and RoutableId in Salesforce Einstein BOT.

{!$Context.ContactId} is used for Contact Record Id.

{!$Context.RoutableId} is used for the Chat Transcript Id or the Messaging Session record Id.

RoutableId is Chat Transcript Id or the Messaging Session Id.

ContactId is the Id of the Contact from Chat Transcript or the Messaging Session.

BOT Builder Configuration:

Output: