I'm trying to upgrade (not update) iPod Touch 6 iOS 6.1.6 to iOS 9 or later. Is this possible?

Hello,

If your iPod touch will not update past 6 then you have an iPod touch (4th generation). You cannot update your iPod touch any further. If you need to use software that requires a newer system software version then you will need to purchase a newer iPod touch model.