I'd be glad to help share some information about expanding the column sizes on your report.
Yes, you're right about the ability to expand the column sizes. And you can still do this using the 2019 version. All you need to do is drag the line column on the upper part. Please see attached screenshot for my sample.
However, you can't save or set this column size as default after closing the report. You can only save the modified settings by adding this to your Memorized Report List.
That should do it. Also, if you need some related references in customizing your reports, you can check the following articles below.