I know, this is an old post, but I am new to Radzen and this was one of my first things I looked up. So for further reference and with the intention to get feedback if I do it wrong (and/or learn about the correct naming), I add what my thoughts:
If you have a "LoadData" context to the right, when your DataGrid is selected you could probably follow this:
Master Detail Hierarchy - How to set default sort - Radzen
For my case, my DataGrid hat an empty "LoadData" section, but when clicking on an empty place on the page, I got to the "page load" context
And there I could add a new parameter
