Depends on what you mean @
Flo Real.
If this was something that happened through millions of years of evolution they may have learned not to fear us although I doubt it as we have weapons, the only animals that don't fear us are the animals who have not been hunted by us, which is very few. They may have evolved to hunt us when given the chance though, If we are alone or threatening it etc. Like Lions do.
If someone made it the size of a horse overnight, it would just be a big duck, it would still act like a duck. It might not be so quick to run away but it definitely wouldn't turn into a predator overnight.