xmlns:customControl="clr-namespace:EntryAutoComplete;assembly=EntryAutoComplete"

<customControl:EntryAutoComplete
            VerticalOptions="CenterAndExpand"
            Placeholder="Enter country..." 
            ItemsSource="{Binding Countries}"
            SearchText="{Binding SearchCountry}"
            SearchMode="{Binding SearchMode}"
            MaximumVisibleElements="5"/>

var entryAutoComplete = new EntryAutoComplete
            {
                VerticalOptions = LayoutOptions.CenterAndExpand,
                Placeholder = "Enter country...",
                PlaceholderColor = Color.LightGray,
                MaximumVisibleElements = 5
            };