This sample loads Datagrid and Chromeless Window with MaterialDark
theme look which has been applied using SkinManager VisualStyle property. Also, it provides drop down options using ComboBox to change themes at run time.
SyncfusionExamples/change-themes-at-runtime-using-skinmanager
This repository describes how to change the themes at run time for datagrid and chromelesswindow using SkinManager
C#