this wont be possible because it has a predefined post page for it. when you click on the services it simply takes you to a predefined template which only show the content in the post.
you added a link, so it showed a link with some excerpt of it. the services post type was not designed to take you to a cusotmized link.
a custom button with option to add a link in the customizer is needed for it. which is not there for the services in the theme it just take you to the content when clicked in an inner blog page.