At some point of overinflation, the tire will pop.
Before that happens, the road handling will suffer and tire wear will be uneven. However, the fuel efficiency might improve some amount.
So a tire that’s tread pattern is perfectly flat with the road is over-inflated? Toyo RT is rated at 80 cold. How can less than half of that be inflated too much? Tires have about 10k on them. Rotated with the spare. No cupping at all. Normal wear. They’re still perfect.