Your head is fat block by xxwarrior001xx

It is pretty simple. You can have any block on your head not item. Command block isn't needed. If you want to change block, simply find

"minecraft:wool" and but something else like "minecraft:dirt". You will get 64 wool. The number 3 on end just changes wool color so you can delete it.

To change how much blocks will you get after "minecraft:wool" you will see 64 so change it to how much you want.