You can achieve the scenario you require with RadGrid by setting the TableLayout property of the GridTableView to Auto whihc allows you to automatically adjust your column widths to widest content in
the column cells. You can refer to the following help link which explains about the different values that can be set for the TableLayout property of the grid: TableLayout Property
I'm looking for something similar too. I don't want to use the Fixed layout because we need to grid to stretch as the user resizes their columns. We want to give the user a way to click a button that will shrink the grid back down to a reasonable size based on the data being displayed. So if they stretch a bunch of columns and the grid gets stretched (good), we want a way for them to basically shrink it down so all data is displayed and not clipped. Not neccessarily to 100%. It might be more. It might be less. It all depends on the data.