It’s plenty unless you plan to sit as close to it as you would a computer monitor. And if that’s your plan for an 85-inch TV, you’re likely to run into other practical problems before noticing pixels come into play. Even if you bought an 8K TV, you still won’t be able to find 8K native content for it, so you’d just be watching upscaled 4K anyway. 4K is plenty. Don’t sweat it.