Heh. Back in the day, I also used heads from The Sims 2 as a source. It had a convenient face customization system and a suitable polygon count for heroes.
But now, some clever guys have come up with a separate tool called iClone Character Creator.

The program is very simple. In fact, it's the same character customizer as in games. But you still need to know English; I'm not sure if there's a translation, although who knows, maybe there is.
The same guys also have a program called CrazyTalk.

The trick is that you can create a model from two photos.
These two programs can work together. So, you can take a face from CrazyTalk and put it into the Character Creator for further refinement.
These models are exported only in OBJ format. To export to something with bones, you need to purchase an additional license. So, in theory, by purchasing all of this, you can legally use the models in your games or mods.
The guy who is making a standalone game from a Skyrim mod uses this set of programs to reduce the cost of the process.
https://m.youtube.com/watch?v=XNTCb8N8yz4
And yes, these are all paid programs, and yes, they can only be pirated. I know there are people on the forum who don't like that very much. But, at least here, you can "pretend" that it was legal. In the case of Skyrim, you understand that this is not the case under any circumstances, unless the model was taken from a mod and the author was asked for permission. But, I'm not trying to moralize here; I don't really care who does what, I'm just thinking out loud.
Added 4 minutes ago
If we're talking about the difference between the regular Skyrim (2011-2012 with all DLC) and the Special Edition (2016), then there is probably no difference, but you need to clarify this with the author of the topic.