As Allen pointed out, changing the size would be expensive. Changing the depth would be much easier. I don't know that doing either would make the pool much warmer, or easier to take care of. It would reduce the cost of chemicals needed to maintain the water, but the amount saved over 100 years wouldn't dent the cost of even a modest remodel.
Spending considerably less than the cost of a remodel on a solar heating system would get you a warmer pool and probably extend your swim season.
And taking the time to study what we teach here regarding pool care, and then practicing it, would very likely reduce the amount of time and expense you're putting into your pool. And/or you could spend some of that money on automation and/or a robot cleaner. You could reduce, and probably greatly reduce, the amount of time you spend adding chemicals and brushing and vacuuming. And still have plenty of money left over to hire someone a few times a year to clean your deck and pool filter for the rest of your life.
There are many ways to reduce the maintenance of your pool that would not only cost you less money, they'd actually save you money from what you're spending now, be less work than even a smaller pool would be if you don't modify your MO, and you'll likely end up with cleaner, clearer water.
So welcome to TFP! If you stick around here, and explore what we teach here, I really think we can put you on a better path than a costly remodel...