When creating a post, we would recommend that the locale be removed from URLs so that a user's preferred locale is default. An exception is if you have a question where the locale is key to the problem to be solved.
For example the localized and delocalized versions of the links you posted,
- https://support.apple.com/en-gb/ios/update
- https://support.apple.com/ios/update
- https://support.apple.com/en-us/HT204306
- https://support.apple.com/kb/HT204306
- https://idmsa.apple.com/IDMSWebAuth/signin?appIdKey=…&language=GB-EN
- https://idmsa.apple.com/IDMSWebAuth/signin?appIdKey=…
If you don't know what the locale-generic version of the page is, check if there exists a canonical link.
The true generic version is the ‘kb’ link, or more recently none at all (thanks @Tetsujin), which automatically redirects to your preferred locale. The canonical link is to help search engines index the correct version of the page, which in this case Apple has selected as the en-us page. You should use the canonical link if you don’t know what the locale-generic version of the page is.
In the case of such a specific link with many parameters that may be time-specific or session specific, or where a locale can't be removed such as specific support pages, link to the previous page's canonical and explain how to navigate to the destination. This helps prevent link rot where the destination page is frequently updated.
Locales in links not a reason to mass edit posts to remove the locale. If you’re editing a post anyway to make substantial improvements or clarifications, then please fix the locale and everything else minor and major that needs tidying up.
Unless a localized link fundamentally breaks a question or is broken itself, this should be strictly followed only when you are crafting your own posts before publishing it.