Customizing DropDown

The height of drop down can be changed using DropDownHeight property.

<syncfusion:SfTimePicker x:Name="timePicker" HorizontalAlignment="Center" VerticalAlignment="Center"  Width="200" Margin="15" DropDownHeight="300" />
timePicker.DropDownHeight = 200;
timePicker.DropDownHeight = 200

IsDropDownOpen

Drop down can be programmatically opened or closed using the property IsDropDownOpen.

ShowDropDownButton

DropDownButton visibility can be changed by using the ShowDropDownButton property

<syncfusion:SfTimePicker x:Name="timePicker" VerticalAlignment="Center"  Width="200" Margin="15" ShowDropDownButton="true"/>
timePicker.ShowDropDownButton = true;
timePicker.ShowDropDownButton = True