so can you do like an exercise to obtain that if you have a shitty tongue tie and narrow palate?

To obtain proper hyoid position? Depending on how bad the tongue tie is you might need correction. My point with the hyoid position is that people who get a "double chin" could possibly be clenching in a way that lowers their hyoid. My other point is that raising your hyoid too far up is also bad, and the only way you can really raise it too high is during a swallow. The hyoid raises above it's natural resting position during a swallow, so the "cheesy smile swallow" advice might be having people's hyoid too high. I think for most people though the hyoid will lower naturally after a completed swallow because keeping it too high feels uncomfortable.

Now that I think about it I don't think it's possible to hold the position of the hyoid during a swallow because the action of swallowing is instinctive and there are many things you can't control during a swallow; breathing is obviously the same. So the action of "holding the hyoid's position" during a swallow is probably impossible anyways since this position of the hyoid only occurs during a swallow and is for the most part instinctive and not something you can control, once you finish the swallow your hyoid should go back to it's normal resting position (ie from swallowing back to breathing, swallowing temporarily stops your breathing). The hyoid has some role in the opening of the upper esophageal sphincter , this is instinctive so to say that you can hold the hyoid in the position that allows for this action to happen is wrong since once you start breathing the esophagus would obviously close so that you can breathe.

I guess my point in this rambling is that there's no point in trying to control the hyoid position if you have correct tongue posture.