Simbakubwa kutokaafrika had a carnivore-like build but was 1000 pounds larger than a polar bear.
African lions weigh up to 550 pounds or 250 kilograms. The largest
land carnivore living today on average is the polar bear. The average
weight of a mature polar bear male is between 900 and 1,500 pounds.
The heaviest recorded polar bear was 2,200 pounds. Simbakubwa
kutokaafrika was the same length as a polar bear, 8 feet from snout to
rump but outweighed the largest polar bear ever by weighing 3,300
pounds, over a thousand pounds bigger than the biggest polar bear ever
That also puts it larger than the short faced bears. This creature was a hyaenodon from the Miocene; technically a time before order Carnivora existed. But it had what seems to me a basic carnivoran body plan. So here you go - a carnivore 1000 pounds heavier than the big bears.
Why so big? Not thermoregulation polar bear style - these things would really have struggled to stay cool at this size in a warm climate. My guess is that large size means large physiologic reserves and the ability to capitalize on briefly and intermittently available windfalls of meat - dead megafauna. It does not have to bring down prey. It just needs to scare off competition. When Simbakubwa shows up, lesser predators and scavengers vacate the premises. When a really big animal dies or is killed, the giant hyaenadon can eat the whole thing themselves. My guess also is that hyaenadons were not social in the manner of modern carnivores who do the same thing, but spread the body mass over multiple related individuals.
A funny thing about this image - I thought it was a real statue at the Nairobi national museum. I was surprised they would have depicted the animal's human companion so lovingly. Anders on his channel states it is a 3d render. No artist is credited so maybe Anders himself? A very Frazetta feel about these two.