Thank you for contacting us. Any time when you invoke the function it measures the strings in the cells and resizes the columns appropriately. You should call the function at any moment you deem appropriate, but there should be some cell values, so that the function can perform some meaningful measure.
You may set the column width explicitly using the Width property. We do not support the stretching functionality out of the box
that you mentioned so you have to write your own implementation about that. I hope this helps. Do not hesitate to write me back if you have further questions or comments.
All the best,
the Telerik team