Is it possible to get young Ryze or triumphant Ryze in hextech crafting?

Triumphant Ryze can only be obtained as a Riot sanctioned tournament prize, without exception. Human Ryze can only be obtained through the original Collector's Edition preorder.

Basically, both are Limited skins and cannot be obtained any other way.

https://support.riotgames.com/hc/en-us/articles/201752944-Guide-to-Legacy-and-Limited-Skins

i believe it is possible to get every champion skin in hextech crafting. just the more rare skins are much more dificult to get.