how do i get verification code on mac os 10.9.5

Check the computer requirements shown in each link to see if your computer is capable of running that OS version.

How to upgrade to macOS Mojave - Apple Support

How to get macOS High Sierra   

Sierra download

El Capitan

Check to make sure your applications are compatible. .       

Application Compatibility

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.

You upgrade it. Or you use an alternative path such as texts or calls. Or you don’t get verification codes.

Get a verification code and sign in with two-factor authentication - Apple Support