(After several weeks of pants agony that is still not quite over) I think I've finally cracked the code so
have an illustrated darts/fullness/etc pattern drafting master post!
(incl. how to take in women's tops for flat(ter) chests! among many other applications)
If you're interested in dart manipulation specifically, do also check out TheClosetHistorian's video on it! She shows how the pattern makes the shape using paper, and shows more places darts can go on a bodice.