How i enable SGX in my mi laptop

When i restart or Power on my laptop it show , SGX is disable , but i not find any SGX in bio setting

This isn’t really NixOS related (at all), but if your BIOS doesn’t allow changing the state, you can check out https://github.com/intel/sgx-software-enable (not packaged for NixOS).

This repo no longer maintain intel

Sure, but that doesn’t mean that it doesn’t work.