Yes and No
Link smart object files can be layered files that contain adjustment layers today. When you update the external linked files. Whenever you open a Photoshop document that has a linker smart object layer to that external files the smart object layers object will be updated. The smart object layers are not updated unless the documents with a linked smart object layer are open in Photoshop or become opened in Photoshop. If you update the external file the other documents with linked smart objected layers are not automatically opened and updated. You need some to have some process to open the other document in Photoshop to have their smart object layers updated. Layered Documents are not used on the web so any images saved for the web for ther documentes must also be updated,
I'm not sure but affraid using the only Adjustments Layer in external Smart Object isn't possible (for now).
But I hope using, built in Photoshop functionality you can prepare similar effect .
(layers, placed images, some build in scripts (export) o even replace smart object command - maybe try this?
At present you can't have an Adjustment layer in a smart object which applies to any other layer outsdie of the smart object.
(1) layer 1 place an image
(2) Layer 2 above the image make an adjustment layer
(3) turn the adjustment layer into a smart object and it effectively disappears
Even with external file - the adjustment layer needs to have a layer below it to work. If it's brought into another Photoshop file then it looses all of the adjutment properties and becomes an empty layer...
Yeah - i have a work-around with actions etc BUT think with the ability to have external linked files into photoshop files then having adjustment layers would make for a more serious easier workflow.
Something for the development team to add in for future versions...?
The beauty of smart objects is that they're a file within a file; they can contain any combination of pixel vector and type data that a .PSB can, and even be stored in a library for instant access.
The solution you're describing is actually much simpler to accomplish, as adjustment layers are just a set of instructions for modifying all the pixels beneath them. You can store your adjustment layer settings as a preset, and apply them to new documents just be adding the corresponding adjustment layer and calling up that preset.
To make it faster and easier, or if your "recipe" calls for more than a single adjustment, you can save the steps as an action, which you can assign to a function key, or batch apply to a folder or to all currently open images,
There's one more solution for more complicated groups of adjustments, but it's also a bit more complicated to describe, involving exporting your adjustments as a Color Lookup Table.
Smart Object layers are like a protected Pixels layer that can not be changed you add add Smart filters to them and transform them repeatedly because the transform is always of the protected pixels rendered for the object by Photoshop these can not be changed with Photoshop tools. You can clip adjustment layer to Smart object layers. A smart Object layer will never be like and adjustment layer.
THANKS - saving as Presets seems to be the way to go - does mean writing an action to apply the updated preset on all images but that's straight forward.
LUTs - will try and see if they auto update across files.