I have a late 2011 MacBook Pro, What is the latest IOS version i can upgrade to if i am running High Sierra

High Sierra IS the newest macOS that your 2011 MBP can run.

(iOS is for iPhones and iPads)

High Sierra is compatible with iDevices running on the newest iOS, 14.8.

If your Mac has High Sierra, it has the latest release OS. Incidentally, you should know that a Mac runs the Mac OS and iPads and iPhones run the iOS operating system. They are completely different operating systems.