Presumably, you might derive some value from phantom’s explanation. The initial goal is to build awareness of your epiglottis. I recommend paying careful attention while yawning. Stretch and focus on different parts of your throat while yawning in different ways.
I guess in a very literal sense, people can explain that foundation skill but can’t guide anyone else to move internal muscles in the same way that it’s possible to maybe move somebody’s hands while learning to knit or perform a card trick.