You can either do this programmatically and via interaction, it's unclear however which you want to do. Via interaction, you would do something like this:
procedure TForm1.AdvTreeView1AfterExpandNode(Sender: TObject;
ANode: TAdvTreeViewVirtualNode);
begin
AdvTreeView1.FocusedNode := ANode.GetFirstChild.Node;
end;
Note that this code is simply for demonstration purposes, it does not take into account of there are children or not. The specific way you want to implement this will differ from the above implementation.
With the path: Audi\A5 Series\S5 want to programmatically navigate to final node: S5 expanding as we go. Starting from the root expand out to final node and set focus on it.
procedure TForm22.Button1Click(Sender: TObject);
var
n, p: TAdvTreeViewNode;
begin
n := AdvTreeView1.FindNodeByTextAndColumn('S5', 0, True);
if Assigned(n) then
begin
p := n.GetParent;
while Assigned(p) do
begin
p.Expand;
p := p.GetParent;
end;
AdvTreeView1.FocusedNode := n;
end;
end;