This is kind of book I'm talking about for understanding the human form, costs less than half here on the author's website than what it is on amazon: https://anatomy4sculptors.com/product/understanding-the-human-figure/?attribute_select-format=Paperback&attribute_select-language=English
You see all the major muscle groups, all the major bone regions, all the major fatty regions, one section of the body at a time.
It's really not set up to start a modeling pipeline in blender, it's more for like actual literal sculpting in real life, but, this is what I would have learned from a while ago, and it contributes to more accuracy, I learned all the subtle curves and boney regions in a person's face and hips and chest are not just hallucinations and have actual anatomically driven causes.
