One way to view it that if you can reason with the creature to make a deal about not fucking/raping you then it is not bestiality. The question if the creature is likely to agree to a deal is not so important, but if you in theory could make such a deal. A large part of bestiality is having an animal that want pleasure and won’t be denied since it is acting out of animal instinct. If you can talk to creature then we are speaking of different kinds of horror.
With demons it might be sometimes be borderline cases. The demon might act like an animal or threaten they might be close to lose control to inspire fear into the victim. The demon cat that talk would normally not be bestiality, but I can certainly imagine scenes when the bestiality tag i merited because of what the reader will imagine might happen next even if nothing happens.