change color of black-gray cartoon to specific color (ig blue)

I have cartoon with black-gray drawing in it.

How to change black-gray to any other color: i.g blue-grading: dark-light?

See Appendix file

By Skyward FBISD

To change the color of a black-gray cartoon to a specific color like blue, you would need to use image editing software like Photoshop or GIMP. You can adjust the hue and saturation settings to transform the grayscale image into a colored one, applying different shades of blue for dark-light grading.

And yet another convoluted way is via Grayscale mode, then Duotone mode: monotone... then back to RGB mode! I used to use this method before the Gradient Map was introduced as it allows precise colour selection which wasn't easily available via Hue/Saturation: Colorize.