Anvil

Place your left item in the left blue box and your middle item in the middle blue box by right-clicking/physically placing the item. An item should then appear on the right if the two items you placed would create something (such as a diamond sword + a compatible enchanted book). From here, you should see a level requirement appear above the anvil. At this point, you can grab the item on the right, which will subtract the levels needed as you grab it. If you don’t have the levels needed, you simply won’t grab the item.