After some research, my challenge has been solved
In my case I created a file named, single-treatments.php page
treatments is the name of the particular custom post type I’m using so be sure to just substitute your own, WordPress will recognise this as the single page template to use when a permalink that is related to that custom post type, in my case the treatments custom post type is clicked on by the end user.
Next I added the standard loop into that single page file. Make sure you visit the permalinks settings page in the WordPress admin area. This is a strange process but seems to enable the custom post single page template to work in the front end.
After this you are good to go. Custom Posts with excerpts and buttons that can link to another template which shows the post in more detail.