Can steerer tube be made longer?

[Retrorockit]

Holland Bike sells RST steerer tubes separately. I've heard of them being used on Marzocchi forks. Since they fit the same headsets they may be generic. I have one sitting around just in case but I haven't tried it yet.
https://hollandbikeshop.com/en-gb/advanced_search_result.php?keywords=RST+Steerer