The Bug:

You cannot increase the tier of enchantments on items when using the /enchant command.

Steps to Reproduce:

• Obtain a wooden sword and use the "/enchant" command to apply "sharpness 1" to it.

• /give @s minecraft:wooden_sword
  /enchant @s minecraft:sharpness 1

• Use the "/enchant" command once again on the same wooden sword to attempt to upgrade the tier of the enchantment on it.

• /enchant @s minecraft:sharpness 3

Observed Behavior:

You cannot increase the tier of enchantments on items when using the /enchant command. If you were to attempt to do this, the error message, "ITEM cannot support that enchantment" is printed in chat.

Expected Behavior:

You would be able to increase the tier of enchantments on items when using the /enchant command.