An enchanting table and a librarian's book both stop one level below the vanilla maximum. Protection IV is not on the table. To go higher, you combine two of the level below at an anvil.
Eight enchantments go past the vanilla ceiling that way. Sharpness, Efficiency, Power and Impaling reach VII. Protection, Blast Protection, Fire Protection and Projectile Protection reach V.
Six enchantments that are not in vanilla
Two are climate enchantments, and you can get these from a table:
- Cold Protection, armour, four levels.
- Heat Protection, armour, four levels.
Four come only from trade. No table gives them at any level:
- Prospecting, pickaxe, four levels. Tells you how rich the ground around you is. See What is under you.
- Wayfinding, helmet, four levels. Tells you where you are and where you have been.
- Trade Winds, elytra, three levels. It does nothing.
- Seafarer, boots, three levels. It does nothing.
The last two show up in game as "Trade Winds (inactive)" and "Seafarer (inactive)". They were meant to strengthen the wind and the currents in Wind and currents, and they are switched off. Do not trade for them.