Plugins are the most common way to add health bars to a Paper server without requiring players to install anything on their own computers.
If you tell me more about your setup, I can help you choose the best option: Neat - Minecraft Mods - CurseForge Health bars 1.19.3
: Offers extensive customization for passive, neutral, and hostile mobs separately. It includes a settings window accessible via a hotkey (default "B") to adjust scaling and positioning. Plugins are the most common way to add