Example

const columns: ColumnDef[] = [
  {
    headerName: 'Name',
    field: 'name',
    minWidth: 100,
    maxWidth: 200,
    menu: {
      column: true,
      filter: true,
      grid: true,
    },
    formatter: (value) => value.toUpperCase(),
  },
  {
    headerName: 'Age',
    field: 'age',
    width: 100,
    menu: {
      column: true
    }
  },
  {
    headerName: 'Address',
    field: 'address',
    menu: {
      column: true,
      grid: true,
      filter: true
    }
  },
  {
    headerName: 'Children',
    field: 'children',
    children: [
      {
        headerName: 'Name',
        field: 'name',
      },
      {
        headerName: 'Age',
        field: 'age',
      },
    ],
  },
];