You Can Jailbreak iOS 12.4 on iPhone or iPad with unc0ver
A jailbreak for iOS 12.4 has surfaced and is now available using an application called “unc0ver”. The jailbreak exploits could also be used for more nefarious purposes by unscrupulous individuals, and is therefore best to avoid for the vast majority of iPhone and iPad users.
The unc0ver application works to jailbreak any iPhone or iPad running iOS 12.4 with any A7 through A11 device, meaning any iPhone, iPad, or iPod touch that has one of those processors and that is running iOS 12.4 can use the jailbreak on that device. That includes iPhone X, iPhone 8 Plus, iPhone 8, iPhone 7 Plus, iPhone 7, iPhone 6s Plus, iPhone 6, iPhone SE, iPhone 5s, iPad (2017), the original iPad Pro models, iPad Air, and several other devices.
Jailbreaking an iPhone, iPad, or iPod touch circumvents the on-device security to allow for modification of system software and installation of third party software, and it can cause various serious security issues, stability problems, and other problems with an iOS device, and is therefore not recommended.