What adjustment would do this

[ivancopeland]

-basically so the "hue contrast" goes up, as shown?

[Ego Eram Reputo]

You want a gradient from gray to red to become all red?

Option 1: Use the Paint Bucket tool and fill the shape with red. I filled your demo image with two clicks at the default 50% tolerance.

Option 2: If the shape is a regular rectangle, draw a new filled rectangle in red.

[yellowman]

"Monochrome ink on paper" does that, Find it in krisVMD package

Set the primary color with Color Picker and run the adjustment, you may need to increase the saturation after that.

[ivancopeland]

No i want to "turn up the hue contrast" heres a better exmple:

Is this poissable?

[Ego Eram Reputo]

I think you are referring to the saturation.

Try Adjustments | Hue / Saturation + move the Saturation slider up.