How do web clients know a CDN's IP?

Hi fellow redditors, thank you for taking the time to look at my post.

I'm trying to learn a bit more about CDNs and after many hours of researching and reading, there is still one important question that I can't seem to find an answer for.

How does a company (or organization) that uses a CDN to deliver their site make their clients aware that they can send requests to a particular CDN? In other words, how does a client go from requesting a particular site to knowing the IP address of a close CDN edge server and sending its requests there instead?

I can't seem to find any explanations to this part of the CDN process anywhere online. Thank you for your time.