How to make a player or a mob block (Minecraft Citizen's plugin)?

I saw that my friend turned himself into a block with the "NPC Plugin" with a player or mob. So to speak, the NPC has become a lapis block. Does anyone know command or orders?

I would be very grateful for answers.

For this you need 2 plugins: LibsDisguises and ProtocolLib.

Only with Citizens is not possible.

That's funny though. I only have: PlotSquared, Essentials, WorldEdit, WorldGuard, ChairStairs, Citziens, Go Paint, Go Brush, SignEdit, Shopkeepers, SimpleRename, VoxelSniper, MultiVerse Core, MultiVerse Extension, Essentials Spawn, Soup Plugin & HeadDataBase on it. So he did it ^^