Upgrade from macOS 10.13.6 to a higher version?

Hello

I just went through the questions and answers, and when going on the link
we end up on the Apple Store for the High Sierra version but not on the possibility of upgrading to a higher version

For me as well, the issue is that this version is no longer supported by developers of Mac products because Apple has closed
access for recent products to this version,
Mac owners therefore have to either buy a second-hand newer Mac or change version, this is possible in principle and
the key is to know what and how

Personally, I continue my search on the internet, otherwise, the question is whether an interface like Ubuntu from Linux can run current Mac operating systems because I just bought a version of a Mac software recommended by Apple for access to older versions, which are now limited to 10.14 and 10.13 is in a retirement home!
The solution is either to upgrade to a possible higher version, the key being to know which one, or if with Linux it is possible to already use this operating system on Apple, thus on older Macs like with Windows.

This allows to avoid excessive pollution since Macs and computers still work perfectly, only the software and apps are only for the latest models

Thank you for your time, no anger in all this but remaining responsible and reasonable about certain commercial excesses, simply accelerating
climate change and not just that! '(lol)

See you very soon
Goodbye and thank you