Checkbox Enabling

For Xamarin Forms:

I am looking to use checkboxes to enable the next set in a series. I have used x:name to set the names of the checkboxes (Fiore, Leichtenauer and Guards). My goal is to set a if statement to change the IsEnabled to false/true in the code behind when the first checkbox is checked. I seem to be getting an error for the IsEnabled, what should I be using instead? Thank you in advance.

private void CheckBox_CheckedChanged(object sender, CheckedChangedEventArgs e)
    {
        if (Fiore.IsChecked)
        {
            Leichtenauer = IsEnabled(false),
            Guards = IsEnabled(true)
        }
    }