The renderer is a property that customizes the cell (row) of the corresponding column.
Customizing column titles is possible with titleSpan .
PlutoColumn(
titleSpan: const TextSpan(
children: [
WidgetSpan(
child: Text(
'* ',
style: TextStyle(color: Colors.red),
),
),
TextSpan(text: 'column title'),
],
),
);