You are looking for Xtreme, not X-treme.
X-treme - no models with fat tire.
Another company - Xtreme Warrior Fat Tire, do have fatties. In fact, they have nothing but fatties:
(Link Removed - No Longer Exists). Doesn't look like a higher-end maker, but you're probably not looking to pay 3K or 4K. The motor is 1,000-1,200W... well, for off-roading this is nice. On the road (country road, whatever), and without serious hills in Florida, you won't need more than 500W, and your battery will last longer then. Also, I have some prejudice to their front-heavy layout, with motor in front. This is a common feature on cheaper bikes, lowers the costs but affects the handling. They are saying that front drive is better for off-roading, - maybe, yes, but it doesn't sound like you'll be doing off-roading. Looks like Deerfield FL is their hub and the company mailing address. Not sure if they have any dealers anywhere else.
You might also check Big Cat:
https://www.bigcatbikes.com/collections/electric-bikes. Also a lower-end maker. They have a few 4" fatties, a few 2.3" cruiser-style tires - thinner than 4" fat but wider than skinny 1.5" commuter bikes. You might consider cruising tire, btw. Should be alright on country roads.
At this age you might also consider a step-through frame like on their Long Beach models - either 4" tire, or 2.3" .
I realize that a "country" in Florida can be swampy, but if it needs a gas-powered 4WD or ATV, then ebike will be a pain, even with fat tires.