If Western civilization were asked, in the terms of the old Reader’s Digest column, to name the Most Unforgettable Character It Ever Met, it would surely answer, with a single, sighing voice: Paul.

After five seasons on ‘Yellowstone,’ Luke Grimes is finally stepping into the spotlight with his own spin-off, and it’s been a long time coming. The 34-year-old Australian actress talks ‘Ready or Not ...