How to AutoFit the nodes based on the content in Xamarin.Forms TreeView (SfTreeView)

You can auto fit the SfTreeView node height based on its content using QueryNodeSize in Xamarin.Forms.

You can also refer th following article.

https://www.syncfusion.com/kb/11418/how-to-autofit-the-nodes-based-on-the-content-in-xamarin-forms-treeview-sftreeview

C#

Setting node height based on its content using GetActualNodeHeight method.

namespace TreeViewXamarin
{
    public class Behavior : Behavior<SfTreeView>
    {
        protected override void OnAttachedTo(SfTreeView bindable)
        {
            bindable.QueryNodeSize += Bindable_QueryNodeSize;
            base.OnAttachedTo(bindable);
        }
 
        private void Bindable_QueryNodeSize(object sender, QueryNodeSizeEventArgs e)
        {
            // Returns item height based on the content loaded.
            e.Height = e.GetActualNodeHeight();
            e.Handled = true;
        }
        protected override void OnDetachingFrom(SfTreeView bindable)
        {
            bindable.QueryNodeSize -= Bindable_QueryNodeSize;
            base.OnDetachingFrom(bindable);
        }
    }
}

Output