I have tried to upgrade my Efficiency 4 Netherite Hoe with an Effiency 4 Book in an Anvil, but it wasn't possible. I also tried to use the /enchant command while holding the Netherite Hoe, but it said "Netherite Hoe cannot support that enchantment in the chat. It is not possible to upgrade an Efficiency 4 Netherite Hoe with an Efficiency 4 Book over an Smithing Table either.