You can load the SfExpander in the MasterDetailPage in Xamarin.Forms.
You can also refer the folloiwng article.
XAML
Load SfExpander in the Master page of the MasterDetailPage.
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:syncfusion="clr-namespace:Syncfusion.XForms.Expander;assembly=Syncfusion.Expander.XForms"
xmlns:local="clr-namespace:ExpanderXamarin"
x:Class="ExpanderXamarin.Views.ExpanderMasterDetailMaster"
Title="Menu">
<StackLayout>
<Grid BackgroundColor="#f54291" HeightRequest="100">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="70"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Image Source="UserImage.png" HeightRequest="60" WidthRequest="60" Margin="10,10,10,10"/>
<Label Text="John" Grid.Column="1" VerticalOptions="Center" HorizontalOptions="Start"/>
</Grid>
<ScrollView BackgroundColor="#EDF2F5">
<StackLayout>
<syncfusion:SfExpander HeaderIconPosition="End">
<syncfusion:SfExpander.Header>
<Grid HeightRequest="50">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Image Source="home.png" HeightRequest="25" WidthRequest="25" HorizontalOptions="Center" VerticalOptions="Center"/>
<Label Text="Home" Grid.Column="1" TextColor="#495F6E" VerticalTextAlignment="Center" />
</Grid>
</syncfusion:SfExpander.Header>
<syncfusion:SfExpander.Content>
<StackLayout Padding="10,10,10,10" BackgroundColor="#FFFFFF">
<Label HeightRequest="50" Text="Tasks" TextColor="#303030" VerticalTextAlignment="Center" />
<Label HeightRequest="50" Text="Settings" TextColor="#303030" VerticalTextAlignment="Center" />
</StackLayout>
</syncfusion:SfExpander.Content>
</syncfusion:SfExpander>
</StackLayout>
</ScrollView>
</StackLayout>
</ContentPage>
Output