While I can't say I'm familiar with any scientific research or lack thereof involving chiropractic, and generally rank your general knowledge as on par if not better, the idea, as I was sold by my former chiropractor, that over time adjustments, well, adjust, seems to be plausible. — Outlander
The history of chiropractic dates back to a man named Palmer who opined that all illness (as in all, from back pain, to sinus infections, to liver disease and so on) was caused by the inability of the life force to find its way down the spinal column due to an improperly aligned spine. He charted out what body parts were affected by misalignments at each level, so perhaps misalignment of the lower lumbar spine might cause you abdominal pain wheras the mid spine might cause you heart disease. The solution was to align your spine, which meant popping your back and supposedly bringing it into alignment, where you could then be cured of your illness.
Over time, most (but not all) chiropractors abandoned to the idea that their adjustment cured various problems with the organs, but they limited their practice to curing spinal pain, although many still claim that periodic adjustments are necessary for maintaining one's general health. Of course, these "adjustments" don't actually change the alignment of the spine, which is easy enough to observe on radiological studies, which is a good thing, because it you were able to manipulate someone's spine so easily, they'd be paralyzed.
The best you can say they do is treat muscular pain and their efforts are glorified massages. Some chiropractors have stopped cracking backs as they're known to do because that poses some liability risks in the event they hurt the patient. That has caused most to turn to a small spring device that they pop lightly on the patients spine and they claim that aligns the spine. Those devices are particularly stupid, but it is part of the practice. In fact, more than 50% of chiropractors now use that method.
https://www.advancedchiropracticgroup.com/services---techniques/activator-technique/activator-technique-faqs-.html#:~:text=The%20Activator%20Technique%20of%20chiropractic,chiropractors%20use%20the%20Activator%20Method.
To quote John Hopkin's Medicine:
"Acupuncture points are believed to stimulate the central nervous system. This, in turn, releases chemicals into the muscles, spinal cord, and brain. These biochemical changes may stimulate the body's natural healing abilities and promote physical and emotional well-being." — Outlander
That statement does not indicate that accupuncture works. It recites what the belief is, but makes no reference to any study.
The New England Journal of Medicine reports the results of a double-blind study on the efficacy of accupuncture for osteoarthritic pain, finding
"Forty patients, randomly assigned to an experimental and a control group, participated in a double-blind study to assess the effectiveness of acupuncture in reducing chronic pain associated with osteoarthritis. The experimental group received treatment at standard acupuncture points, and the control group at placebo points. Analysis before and after treatment showed a significant (P < 0.05) improvement in tenderness and subjective report of pain in both groups as evaluated by two independent observers and in activity by one observer. Comparison of responses to treatment between the two groups showed no significant( > 0.05) difference.
Thus, both experimental and control groups showed a reduction in pain after the treatments. These results may reflect the natural course of illness, and various attitudinal and social factors. (N Engl J Med 293:375–378, 1975)"
https://www.nejm.org/doi/full/10.1056/NEJM197508212930803
You can do a full review of the literature, but you'll find no supporting evidence for accupuncture for the relief of pain. If you did, then your neighborhood family doctor would be performing it, or at least they should be. If it worked and they didn't do it, then it would build an argument that medical practices are just social voodoos dependent upon cultural norms and not actually empirically based.
The reason this matters is because healthcare is a mulit-billion dollar industry and all sorts of people want to get their hands on some of this money. That has resulted in the "alternative healthcare" industry to emerge where they build upon a narrative that there are all sorts of simple solutions to problems and they flood the market with non-scientific testimonials to support their claims. This is not to say that true medical providers don't cheat, rob, and steal, but they at least have a valid methodology that works if they choose to use it. Alternative medicine does not have a valid methodology, and for that, it's not a valid enterprise.