When I was a kid my family owned a device whose sole purpose was to rewind vhs tapes.
I have an old 6 volt lantern that uses a battery that is 6 inches wide, 4 inches tall, and 3 inches deep.
If I turn it on it gives you almost enough light to actually see where you are going and the battery lasts for about 2 hours.
With two 18650s I could replace that battery for a package 2/3 the size of a pack of cigarettes and run that light for a day or so.
If I replace the bulb in it with an LED equivalent I could probably stretch that out to nearly a week.
Its important to consider amperage discharge too. Can the two 18660s put out the same current as the big rectangle one?
Replacing the old halogen with led would be a big difference. Ot would need basically no amperage. At that point you can attach usb male to alligator clips, clip the ends of the lanterns battery pack connectors to supply 5v 2.4a of power directly with a power bank.
I use a 5 volt led bulb that plugs into regular usba slot. It works with small power banks and ast forever on larger 20ah batteries.
Ouch I remember thouse fat 4.5 volt battery who had like 2 long tongues, going into those old flashlights, glowing in the dark at best with a super small incandescent lamp.
These?
https://commons.wikimedia.org/wiki/File:4,5V-AA-battery.jpg
I’d forgotten that they existed. I used to use them for something, maybe powering a Lego or meccano motor.
