I heard putting alkaline batteries in a fridge extends the battery life, so does it really work? By how much percentage does it extend the battery life? Is it worth it?
But even if they’re putting out less power, it’s still enough to operate whatever needs the battery discharge, right? Therefore making it able to conserve more energy, and therefore last longer?

if you take regular batteries to the arctic, they will get so cold that their output will fall off significantly.
If you have batteries that are getting tired, then warming them up, in your trouser pockets can get an extra burst of life out of them.
Simples, no?