And your question is?
Yes, there are adjustable stems. Both for quill stems and aheadset stems.
Most are angle-only. A select few are angle-and-reach.
They are generally seen as OK for fit testing purposes, but to be replaced ASAP with a fixed stem offering the desired rise and reach.
Me, I’m not so categorical.
Sure, I realize they’re heavier than a fixed stem.
And I’ve seen a couple that have developed an annoying play during use.
But IME, the weight penalty overall isn’t much to moan about.
And - If tightened correctly after adjustment - you need to put out some serious watts before the flex coming from being adjustable becomes a valid issue.