i need an upgrade

Your Mac originallly came with Snow Leopard (10.6). If you have never updated it you can upgrade to El Capitan with this link:

http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg

Note that this is a direct link to start a download, and you should use Safari.

Once you have performaed this upgrade, or if you have already upgraded to Yosemite, Mavericks,or Mountain Lion, you can upgrade to High Sierra using this link (in Safari)

macappstores://apps.apple.com/us/app/macos-high-sierra/id1246284741?mt=12

(Paste this into the address bar to open the App Store).

Or use the links near the bottom of How to get old versions of macOS - Apple Support

Notation - The below can only be performed from a Computer that Qualifies to run any of the below versions of macOS

As the by-line in your profile shows MacBook Pro Apple Silicon - this specific computer can not be used to download the requested versions of macOS

That is against the Apple Licence of Use Agreement. Even if the intent is to use the software on an older Qualifying Computer

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.  For Best results use Safari to commence the download as Others may not work.

Safari will open a redirect and open the Apple Store where the download can commence.

macOS High Sierra 10.13 hardware requirements This is the Last version of macOS this computer Qualifies to run

macOS Sierra 10.12 hardware requirements

OS X El Capitan - Technical Specifications

Make Time Machine Backup  is very useful and can be used to Revert to Previous Working macOS