That’s a good question.
So I’ll relate it to your field.
Are added car/foot patrols the ONLY way to stop crime? No. Do they help? Are they needed? In some cases are they exactly the perfect things for certain situations, Absolutely.
It is the same with postures. Postures are a small part of a much larger picture, just as handcuffs are only one thing on a utility belt. It just so happens that postures is what pop culture has brought to the surface and popularized. But poastures are only a sliver of the larger tree.
That having been said, of course there are postures that MAY be helpful. However it is far more on-target to be assessed (since you are unique) by a trained teacher before assembling a series for you. You know, you can by a suit off the rack and you get a suit that fits off the rack. Or you can have a suit tailored and wear a suit that fits you perfectly.
If you are interested in what yoga might offer you to manage BOTH your stress level AND your neck/sacrum issues (though they cannot be separate animals) simply go to a few classes and when you go, go gently without a desire to do anything in particular, to perform, to compete et al. Just go for the going and see what comes of it.
I would suggest something not too intense, not to fast, not too fiery as that may feel “okay” or even “good” but may ultimately add fuel to a burning flame rather than easing an aggravated nature. Calm, calm, calm, even if you are initially resistant.