Training is time to try and apply what works for you. I been using different cues nearly every set lately just to feel stuff out, especially in my warmup sets.
I like Chris Duffin’s cues in one SuperTraining video he shared of:
Expand the obliques
Draw the ribcage in
I personally put alot of respect and trust in Chris Duffin’s word because he’s the biggest powerlifitng name in my area (we’re both Greater Portland Oregon area), and all the coaches are in some way affiliated with him.
I personally have an issue with my upperback overextending, so rounding forward a little (thoracic flexion) and drawing my ribcage in, and depressing my lats works for me. This is a cue I saw on YouTube from John Paul Cauchi.