Bob's saying no to your original question. Graded paper does not give you different contrast grades in response to changes in color, you only get different exposure times depending on how much "actinic" light gets through (think opposite color of your safelight ... blue).
If you want longer print times, adding M + Y in equal amounts can cut the light, like a neutral density filter. As IC-Racer pointed out, by design, these are numbered using "as-if densities" without the decimal point, making 15 a half-stop 30 a whole stop etc.
As Thomas pointed out, changing contrast (often hear it is up to a half-grade change) can be done by changing the developer chemistry. You could also intensify your negatives. You can also dodge and burn to extend darker and lighter tones than a straight print would deliver. I consider all these options when the negative doesn't match the paper I want to use.