Want to buy imac 2013, can you upgrade iOS?

I'm looking into buying an iMac as my windows software is slow and outdated. On the iMac can you upgrade the iOS like you can on iPhones? You know when the new iOS comes out and pretty much all iPhone users can upgrade there software, can you do that on the iMac 2013?

IMacs don't run iOS. New releases of the OS usually cost about $30 for iMacs.

You might want to consider a Linux PC instead; the updates are free and so is most of the productivity software. Games are extra, but otherwise it's pretty inexpensive all around, and it's a great alternative to both Mac and Windows. I have a few friends who have gotten great comptuers from https://www.system76.com/