How to override column width in DataGrid?

[githubkgp]

While grouping columns in datagrid, if the width of data in last column to be grouped is small, then data in rows that are grouped above are partially shown. May I know how can I define width of columns so that entire data is shown? Is there a way to achieve this without defining custom data grid. Below is the screenshot from one of the examples in repo

Expected: Entire column data to be visible