new OS for MacBook Pro 2011

Why can't I update my MacbookPro 2011 to the macOS High Sierra?

Don't know why not since it falls within the High Sierra requirements. What happens when you try?

https://support.apple.com/kb/sp765?locale=en_US

There is a limit so you cannot update to macOS 13.6 but you can upgrade to macOS 13.0 at least.

You just need a installer for 13.0