Hi there,
You used the Feature Box element which does not have such a functionality. Alternatively, you can use custom CSS code to have something like the one you are looking for. As this is a customization we do not offer the implementation as it is out of our support scope, but we can direct you to the right path to do it yourself.
You will need to have a Sold Out image uploaded to your Wordpress installation and have the link available. Then you can add it as a background of the graphic section of the featured box:
.x-feature-box-graphic {
position: relative;
}
.x-feature-box-graphic:after {
content: "";
position: absolute;
top: 0;
left: 0;
height: 100%;
width: 100%;
z-index: 100;
background: url(http://www.freepngimg.com/thumb/sold_out/3-2-sold-out-png-thumb.png) no-repeat center center;
background-size: contain;
}
Replace the background image URL with the URL of your image. Next step will be to have the class option of the Feature Box element and add a class name there. Then use that class name to restrict the sold out for the items you want.
Thank you.