Here's another classic article from the archives of Mark Sowlakis.
Duke Ellington's sax section article
Play a bis Bb, either octave (you pick, but let's say, lower)
Play the Bb, then add a finger & play the A. Go back to the Bb, with the sound of the A in your ear, and WITH YOUR LARYNX, lower the pitch of the Bb to match the A. Then finger the A to compare. Toggle back & forth between fingerings & try to stay with the same pitch (A). You can also play the Bb, slur down to A with your LARYNX, then slur back to the Bb, in time. ("Da Ooh Ah")
Then do the same fingering A, with A to G#, then G to F#, etc...
To start to get the feeling of a "loose larynx", play a C major scale "backwards", in other words, start on middle C, but HOLD DOWN THE OCTAVE KEY & try to play a descending C scale in the lower octave whilst holding down the octave key. Don't worry about tone; just see if you can make the pitches, it’s going to sound like crap.
See how far you can go. See how far you can go after doing it a week...a month..
Then play the ascending C scale, from middle C to high C, with the octave key OFF. That exercise will help you understand the feeling you need in your larynx to accomplish the other stuff.ALSO: