While it's possible to autofill a "User" field type using the "Current User" that's logged into an Interface, it is not possible to auto-link a Linked Record using the currently logged in user.
Use case: We have a custom table of our users that contains a number of fields including the user's email address. We would like to have the option to autofill (set the default value) of a linked record to the current user that's creating a new record in an Interface form. Currently the user has to select themselves out of the list and this adds an extra step to creating a new record and introduces opportunity for data entry errors (e.g. mistakenly selecting a similarly named user)
Example 1: Shows the properties of a User field where "Current user" is selected as the Default Value
Example 2: Shows the properties of a Linked Record where there is no option to use the Current User as a default value to auto select the correct linked record.