Moving font in Minecraft?

I recently saw that you can make red, on the spot / very fast changing font in Minecraft and wanted to ask if who knows how to do that?

Could you describe the writing a little more precisely?

If it was in mid-air, it was surely a hologram. You can do this on your own Spigot server with the following plugin:

https://dev.bukkit.org/...c-displays

I can't describe it that well, but I mean that you rename an object in the anvil so that it is called differently

Was it on a sign, and if so, was it real letters?