The Hieracosphinx is a lesser Sphinx that does not have an official stat block for 5e, as via Christopher Perkins' Twitter. However, I would like to use this monster in a desert setting with Level 6 characters, for which the more powerful Gynosphinx (CR 11) and Androsphinx (CR 17) are out of question for being too powerful and not evil. In 3e, which I'm not at all familiar with, the Hieracosphinx had a CR of 5 apparently, see here, but I have no idea if I could translate the stats 1 to 1 into 5.
Another idea that I had was scaling up a Griffon (CR 2), giving it the Gynosphinx's Claw Multiattack, a bit more HP and a few spells from the spell list.
So, how do I make a Hieracosphinx for this edition? I have never designed a monster from scratch before, only adding or subtracting 1 or 2 things from existing monsters sometimes.