Maybe check out a Red Wings store if you have one nearby. They can measure your feet and order or make you boots. I've had this done for 9" logging boots and they were a little under $300. They have held up well and I expect to get many years out of them.
I would suggest calling the manufacturer of your old boots or checking with the popular brands. Shoe repair places might be able to order them in for you too.
My husband has 4E feet, and finding safety boots that actually have a larger toe cap was impossible. A few years back this company started up here and they are great!
If you need something off the shelf or just don't want to wait for a custom boot. I would recommend the timberland pro boondock. When I worked at a boot store that was the boot I sold all the big guys with really wide feet. It has an extremely wide toe box for people whose toes stick out. It is only going to be listed in medium and wide. But the medium is really wide and the wide is really extra wide. I only sold the safety toe so I don't know what the soft toe is like but soft toes always feel wider.
Yeah they do look a little like clown shoes but they are big wide and very comfortable.
Oh I just saw the 6E sorry. Honestly first if you can find a store with them give them a try because their wife really is wider than 2E. Also if I remember correctly Carolina makes one or two boots in a extra extra wide. We had one guy who needed a something like you need and I think we were able to get them from Carolina. Obviously not something anyone would have on the shelf, but it was a normal production boot. So it cost the same and didn't need extra time for a custom boot
I think we got him these, but I don't remember for sure. They say 4E, so not sure if they will work for you, but I do remember this guy has tried every and that was the first boot he didn't rub this toes in.