I have the same issue but it’s caused by texture pack. Remove the texture pack & the items that are large with the texture pack equipped no longer become large. This happened with an apple & Sugar cane (not sugar). You can see it’s not just in third person either. This started happening after the latest update. I tried experimenting & it doesn’t happen with a golden apple but but regular apples.
Karrot
I have the same issue but it’s caused by texture pack. Remove the texture pack & the items that are large with the texture pack equipped no longer become large. This happened with an apple & Sugar cane (not sugar). You can see it’s not just in third person either. This started happening after the latest update. I tried experimenting & it doesn’t happen with a golden apple but but regular apples.