Hi Ramya
Thanks for reaching out.
It seems that you are trying to link the featured image of the category page of Custom Post Type, you can do that by adding the archive page for that specific custom post type.
Before you add the archive pages for the custom post type, please go through the template hierarchy of the WordPress and the custom port type templates.
And if you are not proficient with the coding, I would suggest you hire a developer who can assist you to do this customization.
And regarding the image size, you use the following code to adjust the size in the specific screen to 100%, please copy the code and add that in your Theme Options > CSS.
@media (max-width: 480px)
{
.category .entry-content.content img
{
max-width: 100%;
}
}
You may need to adjust the breakpoints as per your need. You can find the details on the custom media query breakpoints: https://medium.com/@uiuxlab/the-most-used-responsive-breakpoints-in-2017-of-mine-9588e9bd3a8a
NOTE: And please update the X theme to the latest version i.e 7.2.3 to avoid any version compatibility issue with the latest version of Cornerstone.
Thanks