There are plenty of jailbreak apps that are available on the Cydia App Store. The good thing about these apps is that they open up the iPhone to do things that are not possible to be done without jailbreak. Suffice to say that once the user has jailbreak their device, it opens up to a lot of possibilities for their iPhone. One of the things that they can do is install an app called ManualCorrect which helps improve the autocorrect on the iPhone.
The autocorrect is a good feature but needs to be improved especially since not many people write the full wording of a text. While ManualCorrect still cannot modify the AI behind the autocorrect feature, it can still give some hack on what the user can do with it. One of it is enabling the tap to correct feature on which a tap on the word would immediately correct the wrong spelling. This is much better rather than the default autocorrect setting as you can choose when to do autocorrect.