I have the Zeus power chair from Discover Your Mobility. It has a 24 inch seat and the arm rests are 26 inches apart. It also has a 660 pound weight capacity and they make a mod kit to widen the armrests. It’s pretty comfy for me at 5’6” 570+ pounds. And the best part is that it folds up to fit in a standard car trunk. You will need a ramp to get it in and out of a car though because it weighs 110 pounds.
I got mine second hand. I’ve heard that they are hard to find new because they are very in demand. But Ranger makes a nearly identical chair called the Magnum which has an even wider 2XL version. Which takes the wheelbase from 26 inches to 28 and has a wider seat. The Ranger Magnum is pretty easy to find and is even available on Amazon. Chairs with a weight capacity over 500 pounds are pricey though at around $3,500-$4,500 USD. So if you can get one secondhand in good condition I highly recommended it.
You should keep in mind that extra wide wheelchairs for fat people will struggle to fit through some doors. So you may want to get the narrowest chair that can accommodate you. I’ve only had my Zeus power chair for about 2 weeks and I’ve already found a few doorways and spaces that it’s a struggle to fit through at 26 inches wide. For example I am going to take a trip on Amtrak with my power chair in a month or so and the max width they can accommodate is 27 inches.