link to MacOS Sierra 10.12 is not working. Any other options where I can download it?

The link below can be opened in any browser,

How to get old versions of macOS – Apple Support (UK)

If you had asked for links to install macOS High Sierra 10.13, Mojave 10.14 or Catalina 10.15 I would have said that you needed

to use your Safari browser.because the links contains in the article above redirect you to the App Store where you can get those

As you asked for a link to download macOS Sierra it is not entirely necessary to be using only the Safari browser,

the downloads for Yosemite, El Capitan and Sierra can be done from other browsers.

Here are screenshots of me downloading the macOS Sierra disk image via Firefox.

I must say though I am on a mac running macOS Mojave 10.14..6

And Firefox version 90.0.2.

If your Mac shipped with a newer version of macOS than Sierra, or you are running an operating system newer than Sierra, then the Mac App Store, when exclusively using Safari, will not allow you to download the full installer from How to get old versions of macOS. That is the only source of trusted macOS full installers from Apple.

The first paragraph will be successful if attempted on a Mac running Sierra, or an older release of macOS, and meeting the hardware requirements for Sierra from that preceding link.

The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.

With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install. Make sure to use Only Safari to commence the download as Others may not work. Safari will open a redirect and open the Apple Store where you can commence the download. If an error message appears, that is probably because one is using another Browser.

Suggest using Go64 to find 32 bit application before attempting the upGrade. Some or many of the Application already installed may required update or upGrades to 64 Bit Versions.

Make a Time Machine Backup Before attempting. Notation - Mojave is the Last version to support 32 bit applications / extensions and Drivers. Catalina & Big Sur supports only 64 bit and there is no workaround.

Are there any AntiVirus, Disk Cleaner, Optimizers, Un-installers, etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation

If you do have an operating system on your mac and it is functioning then you can download

Sierra using this method.

How to get old versions of macOS – Apple Support

Go to Download macOS and click on macOS Sierra 10.12

This downloads InstallOS.dmg to your Downloads folder.

The next section can only be done on a mac that is capable of running Sierra,

a mac that came preinstalled with an OS later than Sierra will refuse to do the next bit.

When downloaded open to get InstallOS.pkg, double-click on

that and an installation window will open, read and follow the prompts,

this does not install Sierra but uses the InstallOS.pkg to create the 

Install macOS Sierra.app which you will find in your Applications folder.

 (If the installation window asks which disk you want to install to, you must pick 

the disk that you are booted to at the time. Not any internal or external disk that 

you want to eventually install Sierra on, that is for later.)

To start the installation of Sierra double click on the Install macOS Sierra.app.

The copy of the install app self deletes after installing Sierra, so make sure you keep a copy of the InstallOS.dmg

if you need it in future, or you could just make a copy of the Install OS X Sierra.app prior to installing and moving it to

an external drive for safe keeping.