The current wall is block but plasterboard and plastered. My new wall is studwork with plasterboard. This will join (in the corner with the existing wall).Depends.
Block walls?
I used PVA along the cut board edge to seal and used adhesive all the way along so it's solid. No movement so I never bothered with a corner tape.
If timber stud wall or using foam id run a corner tape down plasterboard as that can give a bit