Your engine is designed to cruise down the highway at the speed your vehicle can go up too.
So just speeding at those high speeds won't do any damage to your engine and the air coming into the engine bay and your radiator will keep the engine cool.
Running your engine at high RPM allows the condensation to burn off out of the oil so you keep your engine in better shape cruising down the highway than you do if you just drove around town.
However if you constantly just step on the gas from a dead stop and floor the gas pedal then that can put too much strain on your engine.
That also causes your bearings to not get the proper amount of oil at the time which can then lead to bearing damage.
It's best to slowly take off by depressing the gas pedal to accelerate and then gradually bring the engine RPM up to get up to the speed you need to go.
But avoid flooring it to take off from a dead stop or you might need a new engine sooner.