I have a One Plus9 phone with recent Android 12 update. How do I get the icons at the bottom that cascade or go to my home screen?

These icons looked like little white outlines of a circle and square at the bottom.  I could click to the center and go to my home screen, click bottom right and all open apps would cascade and I could choose which ones to close.  This is an essential feature that is gone and I don’t know to to get it back.  Please help.