Grades land in the same place
Across the studies worth reading, online and in-person tutoring produce results within about a point of each other for the same number of hours. Anybody selling you one over the other on results is selling you a preference.
Attention does not
Under about thirteen, in person wins and it is not close. Over about sixteen, online wins on consistency — the lesson that survives a wet Thursday is the one nobody has to drive to.
The middle is about the room
Between thirteen and sixteen it comes down to whether the house has somewhere quiet with a door. That is a more honest question than which mode is better, and it is the one worth asking yourself.
You do not have to pick once
Most tutors here do both and the family chooses when the slot is booked. Committing a whole term to one mode because the first lesson happened that way is the actual mistake.