If you hold down right-click while using axolotl spawn egg, eventually all of the axolotls will be babies for a while. However, this is not consistent with the bucket of axolotl.
MC-222573
Bucket of axolotl
Resolved
Works As Intended
0
If you use a spawn egg on a mob with same id, it will spawn a baby mob.
It works on zombies, villager zombies, sheep, cow, etc.
It's not strange that the spawn egg and bucket have different behaviors.