1080ti doesn't hit 60 fps at 4k, unless u scale settings down drastically its more a 30 fps card for 4k
I'm pretty sure I played many games fully maxed out at 4K at 70-90FPS, some even 90-120 on my OCed 1080Ti... Depends on the games/engines - Doom/Wolfenstein, Battlefield/Battlefront, CoD, Forza Motorstorm/Horizon to name a few run well above 60, while others like let's say QB, PUBG, TWC3, RDR2 have a hard time hitting 60 even at 1440p if you really want every single setting cranked up to the max.
That being said, lowering or even disabling the "invisible" options like I like to call them easily allows the card to run the vast majority of games at 4K60. And no matter how many options you'll have tweak down by a notch or two the games will still look and run much better than on consoles, going for Ultra at all cost is just fucking dumb, it's like complaining a car cannot hit 60mph only because you refuse to change the gears, you're just hurting yourself on purpose.