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

System.Configuration.ApplicationScopedSettingAttribute

Specifies that an application settings property has a common value for all users of an application. This class cannot be inherited.
namespace System.Configuration { public sealed class ApplicationScopedSettingAttribute : SettingAttribute { public ApplicationScopedSettingAttribute(); } }