The Latissimus Dorsi (Lats) are depressors and internal rotators of the shoulders. When they are shortened or 'too tight', they can cause mechanical compensations at the neck, shoulders, AND low back!
Shortening of this muscle can cause the 'hunched' or 'turned-in' shoulder posture and it can also promote a pull into an anterior pelvic tilt posture.
Here is an example of cupping treatment to the insertion aspect of the Lat
Here is an example of manual release to the Lat (and some subscapularis)
Here's how to assess for it and an example stretch.
Best physical therapy practice looks at the whole body. It is not only connected from head to toe, but also from inside out; meaning, the joint to the muscle to the fascia. All aspects influence your mechanics. Homing in on the area of pain rarely resolves the issue and definitely does not address where that pain is coming from nor how it developed. Getting rid of the pain can be efficiently addressed; it's WHY/HOW you got that pain that takes longer to resolve.