Announcing Engagement vs Bounty Targets

[Muleo]

So there's either a rule or common etiquette of announcing the intentions to open fire. Does this apply to bounty targets? Surely not, it would be foolish to inform the target as it gives them a chance to flee.

Actually, ESPECIALLY in the case of bounty targets.
Most employers will require you to announce, that they have a bounty on their head, and from whom.
Then kill them. Otherwise they just get killed and they don't know why they're being hunted.