Hologram exists
Whether a hologram with that name is in the world.
A Minecraft element (a check) in Plugins. Needs the Basic plan or higher to go live; building and testing are free.
Example
When the server starts → If Hologram exists: welcome is not → Create a hologram.
Also called
has hologram, hologram there, hologram check
Works as a data pack?
No. This one needs the Elementium plugin on a Paper server.