Hi Nicholas,
You can definitely set the column and row width from the Block properties.
On reading the description, it gives me a feeling that you wish to resize the column widths as per the number of columns fetched so that they could fit the page from margin to margin.
As far as I know there is no direct way to change the column width dynamically. You might try to search for some SDKs related to this issue.
Regards,
Yuvraj