Blender uses the metallic workflow but isn’t friendly towards Specularity if you want to make a cycles render.
This is a short Tutorial on how to get Colored Specular textures to work in cycles. I’m making this guide because every tutorial I found online only deals with greyscale images.
This is how the nodes look, specular color in principled base color, set both Metallic and Specular to 1.0. add a diffuse bsdf and drag your diffuse texture there, use a add shader and that’s it.
This is a ball with 2 shaders in eevee mode, Left side is the custom Principled shader and right side is Specular bsdf.
The Principled shader here has specular turned to zero to show the comparison.
Here is both shaders rendered in cycles, specular bsdf is incompatible.