I repetitively do the same edits its similar to a cut out but will included the cast shadow. while a little bespoke it would be great if it can learn behaviour. I cut out the item including its shadow then brush over the shadow using the refine tool

Lasso > around the object on a white background, include the shadow, then quick mask and fill bucket to select the area for the mask, then into  refine mask I brush the shadow, so that the mask allows the shadow to have transparency.

So while its similar to select subject, select subject and its cast shadow.

Its something I do repetitively and would be great if it could learn from me.