How does a site dominate keywords with multiple URLs directing to one page?

While my company website struggles to appear on the first couple Google search pages, I discovered that our competition is dominating local searches by putting in a url like:

https://site/town-keyword-longtail (I don't want to post the actual link)

So they have a different page with the same basic content for each town. But then I noticed that if I searched for a related keyword string, they dominate with that URL string too.

But this "/town-different-keyword" seems to be land on the same page. So have they set up duplicate pages on their site for each keyword variation (which would be massive and I assume would be flagged for duplicate content), or have they set up redirects (or something else) that allow a single town page to rank with multiple URLs?

And how can I do that on my company Wordpress site?