It is possible to use multiple colors when knitting.
To get the detail/shadowing you want you would need to use fair-isle/stranded knitting and switch colors every few stitches.
Using smaller/thinner yarn would be better if you want a detailed image. You will have to knit more stitches to get your overall size, but you will have better control over the smaller shapes within the image (curves can look like curves rather than steps).
Here's some inspiration