For a new car I would avoid driving above 55 MPH for at least a few hundred miles to allow the oil to break in with the engine and allow the transmission to take it easy for at least those few hundred miles and then you can drive at higher speeds without issue.
When you buy a brand new car it's recommended to take it easy for at least the first 1,300 miles.
But as long as you take it easy for at least a few hundred miles before doing a lot of highway driving then you're not gonna harm the car.
Usually though after I buy a new car I drive easy for 200 miles at first and then I go ahead and drive it out on the highway at higher speeds like normal.
I also change the oil in the cars engine after 1,500 miles because there usually are break in oils in the car and you might get some metal shavings out of the oil from the engine manufacturing process.
Then I go 5,000 miles again before changing the oil and oil filter.
Cars are a machine though and are meant to be driven so you don't have to take it easy for too long.