HandyControl/src/Shared/HandyControl_Shared/Themes/Styles/Base/LoadingLineBaseStyle.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:hc="clr-namespace:HandyControl.Controls">

    <Style x:Key="LoadingLineBaseStyle" BasedOn="{StaticResource LoadingBaseStyle}" TargetType="hc:LoadingLine">
        <Setter Property="DotDiameter" Value="5"/>
    </Style>

</ResourceDictionary>