In STORES > Configuration > CATALOG > inventory I have "Display Out of Stock Products" set to "Yes.
I can get Simple Products that are out of stock to appear but I cannot get a configured item that has a quantity of 0 to appear on the product attribute drop down list on the public side of the site.
How can I get configured products that are out of stock to appear?
Default Magento does not provide this functionality. So you need to customize Magento to some deep level. But according to me, change in magento is not good and recommended.
Can you tell me why you are in need of such requirement so I can provide you with an alternative suggestion if possible.
We want the customer to know that we carry a certain attribute (e.g., size) for the product but just do not have it in stock at the moment. Hoping the customer will wait or come back vs. leaving us for another option elsewhere.