<PackageReference Include="System.Configuration.ConfigurationManager" Version="11.0.0-preview.2.26159.112" />

System.Configuration.Internal.IInternalConfigConfigurationFactory

Defines the interfaces used by the internal design time API to create a Configuration object.
namespace System.Configuration.Internal { public interface IInternalConfigConfigurationFactory { Configuration Create(Type typeConfigHost, params object[] hostInitConfigurationParams); string NormalizeLocationSubPath(string subPath, IConfigErrorInfo errorInfo); } }