Avalonia/samples/ControlCatalog/Pages/CheckBoxPage.xaml

<UserControl xmlns="https://github.com/avaloniaui">
  <StackPanel Orientation="Vertical" Gap="4">
    <TextBlock Classes="h1">CheckBox</TextBlock>
    <TextBlock Classes="h2">A check box control</TextBlock>

    <StackPanel Orientation="Vertical"
                Margin="0,16,0,0"
                HorizontalAlignment="Center"
                Gap="16">
      <CheckBox>Unchecked</CheckBox>
      <CheckBox IsChecked="True">Checked</CheckBox>
      <CheckBox IsChecked="True" IsEnabled="False">Disabled</CheckBox>
    </StackPanel>    
  </StackPanel>
</UserControl>