public bool IsSingleWorkspaceEditSession {get; set;}

// ApplicationOptions.EditingOptions.EnableEditingFromEditTab is true
// ApplicationOptions.EditingOptions.IsSingleWorkspaceEditSession is true

// find a layer
var mm = MapView.Active.Map.GetLayersAsFlattenedList().FirstOrDefault(l => l.Name == "Roads");
if (mm == null)
  return;

var project = Project.Current;
var success = await project.SetSingleEditWorkspaceAsync(mm);

// if success = true then an edit session was started
// and project.IsEditingEnabled will be true

// ApplicationOptions.EditingOptions.EnableEditingFromEditTab is true
// ApplicationOptions.EditingOptions.IsSingleWorkspaceEditSession is true

var project = Project.Current;

// check if already editing
if (project.IsEditingEnabled)
{
  // save or discard any edits
  if (project.HasEdits)
  {
    var res = MessageBox.Show("Save edits?", "Save Edits?", System.Windows.MessageBoxButton.YesNoCancel);
    if (res == System.Windows.MessageBoxResult.Cancel)
      return;
    else if (res == System.Windows.MessageBoxResult.No)
      await project.DiscardEditsAsync();
    else
      await project.SaveEditsAsync();
  }
  // close the edit session
  await project.SetIsEditingEnabledAsync(false);
}

// find a layer
var mm = MapView.Active.Map.GetLayersAsFlattenedList().FirstOrDefault(l => l.Name == "Roads");
if (mm == null)
  return;

// start the edit session on the workspace attached to the layer
var success = await project.SetSingleEditWorkspaceAsync(mm);

// if success = true then an edit session was started
// and project.IsEditingEnabled will be true

// setup the configuration to edit the data registered as versioned in the egdb
var datastoreConfig = new DatastoreConfiguration(egdb, VersionState.Versioned);

// start the edit session on the workspace
var project = Project.Current;
var v_success = await project.SetSingleEditWorkspaceAsync(datastoreConfig);

// OR 

// setup the configuration to edit the data that is not registered as versioned
var nonVersionedDatastoreConfig = new DatastoreConfiguration(egdb, VersionState.NonVersioned);
// start the edit session on the workspace
var nv_success = await project.SetSingleEditWorkspaceAsync(nonVersionedDatastoreConfig);