Apply Themes
You can apply the Light and Dark built-in themes to DevExpress Xamarin.Forms UI controls to change their appearance. The following images show these themes for DataGridView:
The Theme class stores available theme names. To apply the theme, assign a Theme class’s appropriate field to the ThemeManager.ThemeName property.
using Xamarin.Forms;
using DevExpress.XamarinForms.Core.Themes;
// ...
ThemeManager.ThemeName = Theme.Light;
InitializeComponent();
// ...