There are ways to "change" grades during paper development. But they are tedious. Examples of ways to do this is to use different developers during the same paper development, like using Dektol in a bath and then Selectol-soft in another bath.
But as I said, this is very tedious and I think very unnecessary. So my suggestion is, just use the papers and see if you like the images. Who knows, sometimes things may turn out wonderful!