Cyanotypes do tend to be high contrast in plain water baths. You do have to tailor the neg to the process. Yet if all your negs print with too high contrast, try a weak solution of citric acid in the water bath to immerse the exposed prints in. This expands the print values tremendously! Be careful though as cyanotypes go absolutely nuts in acidic solutions--sensitizer on the paper quickly leaves the paper surface and goes into the bath, then lands on and can stain the unexposed white high values in the print.