public class BaseModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        protected void OnPropertyChanged(string propertyName) 
            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    public class Person : BaseModel
    {
        public string Name { set; get; }
        public int Age { set; get; }

    }
    public class MainModel : BaseModel
    {
        public MainModel()
        {
            _persones = new ObservableCollection<Person>();
            int count = 100;
            while(count-- > 0)
            {
                _persones.Add(new Person() { Name = $"Person #{count}", Age = 20 + count % 10 });
            }
            Persones = new ListCollectionView(_persones);
        }

        internal void RemovePerson(object currentItem)
        {
            _persones.Remove(currentItem);
        }

        private IList _persones;
        public ICollectionView Persones { set; get; } 
    }

    public class RowNumberConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            DataGrid dataGrid = (DataGrid)values[0];
            object value = values[1];
            System.Windows.DependencyObject container = dataGrid.ItemContainerGenerator.ContainerFromItem(value);
            if (container == null) return string.Empty;
            return (dataGrid.ItemContainerGenerator.IndexFromContainer(container) + 1).ToString();
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            return new object[2];
        }
    }

<Window x:Class="DataGridColumn.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:DataGridColumn"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.DataContext>
        <local:MainModel/>
    </Window.DataContext>
    <Window.Resources>
        <local:RowNumberConverter x:Key="RowNumberConverter"/>
        <Style TargetType="{x:Type DataGridRowHeader}">
            
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type DataGridRowHeader}">
                        <Border BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}"
                                Background="{TemplateBinding Background}" Margin="{TemplateBinding Margin}">
                            <TextBlock Margin="0,5" TextAlignment="Right">
                                <TextBlock.Text>
                                    <MultiBinding Converter="{StaticResource RowNumberConverter}" Mode="OneWay">
                                        <Binding RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}"/>
                                        <Binding />
                                        <Binding Path="Items.Count" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}"/>
                                    </MultiBinding>
                                </TextBlock.Text>
                            </TextBlock>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>
    <Grid>
        <DataGrid x:Name="PART_DataGrid" ItemsSource="{Binding Persones}" AutoGenerateColumns="False"
                  VirtualizingPanel.VirtualizationMode="Standard">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Name" Binding="{Binding Name}"/>
                <DataGridTextColumn Header="Age" Binding="{Binding Age}"/>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>