Minecraft NBT change data?

Hey a signed book has NBT = 5 properties after I put this in an anvil it has 6 NBT properties.

With a texturepack I want / want to make a signed book with a certain name look different. If the book has 5 NBT properties that doesn't work but I have 6 NBT properties. Is there a way to set the NBT properties to 6 directly via plugin or something?

The entire item consists of nbt data (which you can manipulate with / data)

The nbt display shows how much special Nbt data is on it in addition to the standard data (which item, which stack size…).

If you name the item, you will add one (the CustomName) and the number increases by 1.

The number has no real meaning. It can change afterwards through normal use (e.g. If the player pulls the book through the anvil again).

The CustomModelData tag is provided for your case: https://minecraft.fandom.com/de/wiki/Anleitungen/Zus%C3%A4tzliche_Gegenstandstexturen_erstellen

With this you can give a certain item a special texture from your pack without losing the basic item.