I have a refurbished 2017 MacBook Air 13" w/ Sierra software but I need Big Sur or Monterey

A mid 2013 MacBook Air can be upgraded to the latest version of Big Sur macOS 11 but no later. See: How to download and install macOS - Apple Support

Be aware that if you upgrade to Catalina 10.15 or later you will also need to update any non-Apple 32-bit apps. See: https://www.macworld.com/article/232735/how-to-check-if-mac-software-is-32-or-64-bit.html

Big Sur a Migration tip - Apple Community

Please note, Catalina and later operating systems will only support 64 bit applications. If you have already purchased applications to add to your Mac, you'll need to purchase upgrades for applications that aren't 64 bit. That's covered in the tip.

See here:

How to download and install macOS - Apple Support