Post Featured Image Opacity

Hi, I am trying to match the theme example at https://themes.ishyoboy.com/kopy/blog-classic/ and https://themes.ishyoboy.com/kopy/peaks-of-your-life/. In the example the opacity on the featured image on the home page matches the post image. I found the settings in Theme Options -> Pattern Options under Tagline pattern to set the image opacity to 60 which closely matches the example home page however when viewing the actual post the opacity does not take affect.

So the question is how do we set the opacity on the post featured image to match the home page as it is in the theme example?