Is there some kind of way to control color ramp node color Strenght (opacity of the colors?)? Something like when in Photoshop you add a solid color adjustment layer and you control the color with opacity value.
You can do this by lowering the alpha value of whatever color you want on the ColorRamp - in the example below, I assign an alpha value of 0.1 to the blue strip in the color spectrum (I know it says .285 in the image - I lowered it for the rest of the example).
By mixing with a solid color and using the alpha from the ColorRamp as a mix factor, I can blend whatever other color I like into the blue (transparent) section. You can make it fully transparent, so the new color shows completely through, or you can make it semi-transparent, and the new color will "mix" with it:
Ends up looking something like this (with my settings):
It's not possible to do something like that with just a color ramp, but you could get creative with the nodes in order to achieve such a result:
Here the "Color" Color Ramp effects the "Base Color" of the "Principled BSDF" as usual, but after that the "Opacity" Color Ramp is the factor between the "Transparent BSDF" (which is an invisible shader) and the "Principled BSDF", which creates this result:
(If you're using "Eevee" you have to use "Alpha Blend" for "Blend Mode" in the material settings in order to see it.)
I hope that this helped you.