Definitely but I don't see any indications that any group of 5E players (whether 20-somethings or 40-somethings or whatever) particularly wants their D&D settings to be like that.
Otherwise darker settings would sell like hot cakes, wouldn't they? And in fact they don't. For your theory to work, there would have to be this unmet demand for that stuff. But the demand is absolutely met. Even beyond D&D, there are tons of "dark fantasy" RPGs, Shadow of the Demon Lord being an obvious one. Are they hideously successful? Not really. They do fine. It certainly looks like demand is met there.
So I would say that evidence suggests that the people who watch GoT and The Witcher, do not want to play out GoT or The Witcher in a TTRPG. YMMV.
EDIT - As an aside, whilst it didn't blow up the world, the Shadow and Bone show for Netflix is based on a series which roughly Witcher-dark, and which shows perhaps a take which is closer to how TTRPG doing "dark fantasy" in those kinds of settings might look. It was successful but I don't think a mind-blowing hit.
Further, I think a lot of it on TV is just about spin. Like, look at the Wheel of Time show. Firstly it's pretty great, I was shocked, the books are dull, but the show starts "Eh" and becomes "HELL YEAH!", but the show FEELS like 10x darker than the books. It isn't. It's the roughly the same events, but for some reason seeing them, hearing them, all that - wow that's a lot scarier than reading them (this is not always the case - I think it shows a limitation Jordan had as a writer but feel free to disagree). So what I would call "normal fantasy" in terms of darkness - WoT - comes across as pretty damn scary. I mean I think you could spin the FR or Eberron to be pretty "dark" if you wanted to. It's just on how you describe things and what you choose to happen.