?RGBColor

Plot[1, {x, 0, 1}, PlotStyle -> RGBColor[0, 0, 0]]

Plot[1, {x, 0, 1}, 
      PlotStyle -> {RGBColor[1, 0, 0], Thickness[0.02]}]

Plot[1, {x, 0, 1}, 
      PlotStyle -> {RGBColor[1, 1, 0], Thickness[0.02]}]

Plot[1, {x, 0, 1}, 
      PlotStyle -> {RGBColor[0.7, 0.7, 0], Thickness[0.02]}]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0.1*qq, 0, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0, 0.1*qq, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0, 0, 0.1*qq], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0.1*qq, 0.1*qq, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0.1*qq, 0, 0.1*qq], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {RGBColor[0, 0.1*qq, 0.1*qq], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0.1*qq, 0, 0, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0, 0.1*qq, 0, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0, 0, 0.1*qq, 0], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0.1*qq, 0.1*qq, 0, 0], 
              Thickness[0.065]}, DisplayFunction -> Identity], {qq, 1, 
        10}]; Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0.1*qq, 0, 0.1*qq, 0], 
              Thickness[0.065]}, DisplayFunction -> Identity], {qq, 1, 
        10}]; Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0, 0.1*qq, 0.1*qq, 0], 
              Thickness[0.065]}, DisplayFunction -> Identity], {qq, 1, 
        10}]; Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0, 0.1*qq, 0, 1/2], Thickness[0.065]}, 
          DisplayFunction -> Identity], {qq, 1, 10}]; 
    Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0.05*qq, 0.1*qq, 0, 0], 
              Thickness[0.065]}, DisplayFunction -> Identity], {qq, 1, 
        10}]; Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]

Do[
      plo[qq] = 
        Plot[0.03*qq, {x, 0, 1}, 
          PlotStyle -> {CMYKColor[0.1*qq, 0.1*qq, 0.1*qq, 0], 
              Thickness[0.065]}, DisplayFunction -> Identity], {qq, 1, 
        10}]; Show[Table[plo[qq], {qq, 1, 10}], 
      DisplayFunction -> $DisplayFunction]