Why can't Safari establish a secure connection to help.apple.com?

When visiting a website that you actually know the URL for, never use a search engine. Instead, type that address directly into the address bar of your browser. By doing a web search for a domain, you run the very real risk of fake search results. It is very likely that the link you are clicking on is not to the legitimate Apple site. Enter https://support.apple.com/ directly into your browsers address bar (not into a Google search) and hit return and it should visit the legitimate site.

Andreakirk17 wrote:

... it’s an old MacBook Pro

How old is "old"?

To learn how to identify its exact model designation please read Identify your MacBook Pro model - Apple Support.

While you are there, identify its macOS version as well: Find out which macOS your Mac is using - Apple Support.

Those details are important so that we can suggest a workaround, if appropriate.

Don't use Google.

... and its macOS version?

Find out which macOS your Mac is using - Apple Support.

Pending that answer, try Firefox. Launch Safari and determine if this link works:

https://www.mozilla.org/en-US/firefox/new/

It may or may not want to install. Firefox kept updating its commensurately "old" version up until a few months ago, but its latest "Extended Service Release" version will work with all "newer" websites, whereas that Mac's version of Safari won't.

Pending your answer Brave might work also:

https://brave.com/

Try it.