Depends on the knee injury. Knees are typically more difficult to injure because it’s a thicker joint with far more musculature supporting that joint (not that it can’t be injured, as we all know). An ankle is a mortise joint with less musculature supporting it, but it has many degrees of freedom, which allows it to be as mobile as it is. Continuous spraining of an ankle tends to lead the ankle to be more immune to sprains after a while (the tendons and ligaments have been stretched to a point that a sprain doesn’t bother them as much anymore), but occasionally a really bad sprain can lead to a rupture of the ligaments, which would require surgery to correct. You damage it badly enough, then yes, you can have chronic issues. I do, for example. Tore my ATFL and now I limp when I run. Never had surgery but my ankle isn’t anywhere near the same as it once was.
For someone like Fox, he will probably feel it for a few weeks as he relies on quickness, but a minor to moderate sprain should not cause any chronic issues.