<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.0" />

System.Configuration.Configuration

public sealed class Configuration
Represents a configuration file that is applicable to a particular computer, application, or resource. This class cannot be inherited.
namespace System.Configuration { public sealed class Configuration { public AppSettingsSection AppSettings { get; } public ConnectionStringsSection ConnectionStrings { get; } public string FilePath { get; } public bool HasFile { get; } public ConfigurationLocationCollection Locations { get; } public ContextInformation EvaluationContext { get; } public ConfigurationSectionGroup RootSectionGroup { get; } public ConfigurationSectionCollection Sections { get; } public ConfigurationSectionGroupCollection SectionGroups { get; } public bool NamespaceDeclared { get; set; } public Func<string, string> TypeStringTransformer { get; set; } public Func<string, string> AssemblyStringTransformer { get; set; } public FrameworkName TargetFramework { get; set; } public ConfigurationSection GetSection(string sectionName); public ConfigurationSectionGroup GetSectionGroup(string sectionGroupName); public void Save(); public void Save(ConfigurationSaveMode saveMode); public void Save(ConfigurationSaveMode saveMode, bool forceSaveAll); public void SaveAs(string filename); public void SaveAs(string filename, ConfigurationSaveMode saveMode); public void SaveAs(string filename, ConfigurationSaveMode saveMode, bool forceSaveAll); } }