How to download the latest version
I am using OS X the version is 10.8.5 and I want to download to the latest iOS.. it is telling me
MacBook Pro
How old is your MacBook Pro? As a minimum, you can install El Capitan using the link below.
How to upgrade to macOS Mojave - Apple Support
You can try to download it at the link below. If it won't let you, then your only options are to upgrade to Sierra/High Sierra/Mojave or find an older computer where you can download it using your Apple ID.
Check to make sure your applications are compatible.
El Capitan 10.11 Compatibility information
macOS Sierra 10.12: Compatible Apps
Also check to make sure there is a compatible driver for your printer.
Do a backup before installing, preferable 2 backups on 2 different drives.