What are the URLs of apple’s apps?

The problem is harder than you might think. Let me explain...

First, you can get the link to any of these apps by opening the App Store.app, searching for the app in question, then clicking the Share icon and choosing Copy Link:

The reason why it's difficult is that most of these apps have specific versions for specific MacOS versions. Someone running Sequoia (MacOS 15.5), for example may have a very different version (and potentially a different link) from you running MacOS 10.13.

If I gave you a link for Pages for MacOS Sequoia and you tried to open it, chances are you'd get a notice that this app is not compatible with your system (there's a chance - I haven't tested - that the App Store is smart enough to downgrade the link to a compatible version, but I'm not prepared to take that bet :) )

So you will have to collect the links for the version of these apps that you want.

There are no updates for Pages, Numbers, Keynote, etc. for a Mac running macOS High Sierra 10.13.

Go www.icloud.com and log in

There are On-Line versions of Pages, Number, Keynote, Mail, Notes, Find My, Reminder etc

The problem is that the App Store is not set up let you pick and choose old versions.

E.g., the current versions of Pages, Numbers, and Keynotes require macOS Sonoma (14.0) or higher. If you have never downloaded these applications from the App Store before, and want to get older High-Sierra-compatible versions, you are out of luck. The App Store won't offer them to you.

There were some very old versions of the iWork applications (Pages, Numbers, Keynote) distributed on DVD, but I forget what versions of Mac OS X / macOS they require. And, of course, you can no longer order those DVDs from the Apple Store.

If you previously downloaded applications from the App Store, you could try going to the Purchased section and seeing if the App Store will let you download versions that are compatible with your Mac.