What is the latest version for OS X 10.11?

It depends on your current MacBook models there are some models that can't able to upgrade/update with the latest version.

See the list of compatibility from these links below.

- https://eshop.macsales.com/guides/Mac_OS_X_Compatibility
- https://everymac.com/systems/by_capability/maximum-macos-supported.html

Then look for your model and let's see if your device is compatible to upgrade to the 10.13 or above version of OSX.

The recent version is Big Sur macOS 11.0.x

Thank you, but what i would like to know is not how can i update OS X, but what is the latest version of Electrum compatible with OS X 10.11