[Bigotti5]

It depends on the header of the asset

In scenarist the stream has to be encoded as PS (in Sequence header flagged as 4:3, PS in sequence display extension e.g 540×576)
Encoded as 16:9 you cant set display mode to panscan in scenarist.

If the asset match these requirements create a track, mark the track in the left pane in Track Editor, in Property Browser you can set the “Display Mode” to “Only Panscan”