I googled a bit and most people claim that it's not avilable for the 10XX series.
However, I've check an old UE4 video of mine and there it was available. Strange.
Since UE5 upgrade I've got a lot of flickering in all kind of shadows. I tested TSR in Ultra Quality with TSR Quality Epic and I've tested Upscaling Off with Anti Aliasing Epic & Post Processing Epic. In all those cases there is that strange flickering. Gives me headaches after 2 minutes. Basically unplayable.