Yes. While you can manage feature flags and Key Vault references in App Configuration through the Azure portal or CLI, you can also create and update them programmatically using App Configuration SDKs. Therefore, you can write your customized management portal or manage them in your CI/CD programmatically. The feature flag and Key Vault reference APIs are available in SDKs of all supported languages. Check out the sample links for examples in each supported language.
Evaluating and consuming feature flags in your application requires the App Configuration provider and feature management libraries, which are available in .NET and Java Spring. Check out the Feature management section under Quickstarts and Tutorials for more information.