As stated by Paul and Pete no need for an end support.
For finials, I just start and work back leaving as much material on the piece until it needs to be cut this gives plenty of support it just means that you need to do each piece to completion as far as turning and sanding is concerned, never needed the support for those.
For long thin stems as Pete I use my hand to support the centre to stop whipping if needed and then still apply the same principle as turning finials.
If you need to have something at the end for support you would be better off buying something like this
Robert Sorby revolving centre which one of the attachments means you need to make up something to hold whatever you want. It gives you a number of options for different holding methods for different jobs