Near as I understand, the Assassin is still meant to be a mutant even if the studio ditched the others.
Predators on average are roughly 7 feet tall. Some are larger, few are shorter, but on average the Predators are 7 feet tall barring some exceptions. The Assassin is 11 feet tall and if I recall correctly I don't believe any other is that big. Predators can get pretty large but 11 is definitely the biggest. However height doesn't necessarily mean it's a mutant (in terms of genetic augmentation). It could be a case of it suffering from a bad case of gigantism which isn't out of the question seeing as it happens in Humans. As well since Predators are far sturdier than us, they might be able to take it since they already can get pretty big.
No Predator to my knowledge though possess digitgrade legs.
The exoskeleton is also new. They do possess osteoderms so this wouldn't entirely be unheard of for them to have a natural body armor. However the Assassin can form this at will so this is definitely some sort of upgrade.
The vision is also a dead giveaway since it shows a HUD and his vision is filtered to which a Predators natural vision is exceedingly less. I'd imagine that outside of visual and audio sensors that the helmet is worn for protection but since the Assassin in combat is built like a brick shithouse, I'd imagine it's just one more thing to carry.
In terms of strength, the only other cinematic Predator battle is in Predators and they already butcher humans and the Classic Predator was likely weak from being strung up. He still put up a fight though so I'd assume the Assassin utterly crushing Fugitive is meant to be that he is physically stronger even if other feats are accomplished by other Predators.
Though at the end of the day we don't know who is seen on the slab as I don't think the movie makes it clear if its the Assassin, Fugitive, or if it's just another Predator going under the procedure. It does seem to still be meant as a genetic mod.
