Depending on the vintage of your Mac, you may (or not) be able to upgrade to a later version Mac OS X.
..Or maybe a newer macOS. In either case, try reading through this for information; it may or not help..
• How to upgrade to OS X El Capitan 10.11.6 - Apple Support
https://support.apple.com/en-us/HT206886
Some newer systems will not install directly; while they may ~ if correct older ones are installed first.
El Capitan is one of those older ones. This assumes your Mavericks OS may be upgraded past; it may
require El Capitan before going further.
Guessing by now you may have found other clues online; or perhaps concluded this path isn't for you?
In any event, you can read through major databases online; you may have checked everymac.com.
Update and upgrade info for Mac/Apple can also be found within database app, from mactracker.ca.