Static pages without page templates

Hi,
I am working on a wordpress theme for a website(no blog) where the content is almost fixed. There will be a fixed 4 pages. The client will add/delete the individual blocks from these pages, rather than adding a complete page. The theme will put together these components/blocks to render a page.
Now, I used to do this using page templates, like a page template for contact page, a page template for home page, a page template for services page. But this requires there be a page that implements the given template. And at any point client mistakenly deletes any of the page, the site does not work and I get a panic call.

So, is there a way where the theme could define pages, and detect which page to render, without actually need to have blank pages(native page type) implementing specific page template?

The components will be either custom post types or options entered from Redux embedded in the theme. What I need is a way to detect “/services” in the url and render the right components, so addition/deletion of pages wont affect it

Thanks