Copy a layer adjustment value to another psd layer how ?

Both of what @Stephen Marsh mentioned are excellent ideas. I would go with just dragging the layer over. If you use those seeting often, you can also save the layer to your library. One note on that is that if you drag it to a different sized file, you want to press the alt/opt key so it sizes correctly and doesn't leave an uncorrected border.

@Merlin3 

You can manually drag the adjustment layer from one doc to another using the Layers panel, or use the Layer > Duplicate Layer menu command to dupe the adjustment layer from one doc to another.

The alternative would be to save the adjustment layer values as a preset from within the adjustment layer (gear icon), then load the preset into the other doc's adjustment layer.