Wrong metric. Cost per passenger per mile is a better one.

The reason big jets are popular is that jets burn lots of fuel, which is expensive. Bigger jets burn fuel a bit more efficiently so the cost per passenger becomes more reasonable. Big battery electric planes are likely not possible with current battery technology.

But the good news is that small electrical planes are pretty cheap and the electricity is cheap too. So, instead of buying a big Boeing to save fuel, you could buy a few dozen smaller planes, fly to smaller airports that Boeing would not even be allowed to land, and drop passengers off closer to their destinations.