Got the pre-init script enabled?

This requires an additional script block in your tag, described here: New or Returning pre-init script

This is available in our datalayer with the above script. Because of this, targeting is very easy.

Data Object Attribute "new_returning" is equal to "new" Data Object Attribute "new_returning" is equal to "returning"

As described in the above document, there are nuances to where you might want to set these values.

Read more here: Segmenting by New or Returning

That's it! Nice and easy.