First of all, you should understand that Jailbreak for iOS 12.4 and Jailbreak 12.3 does not exist yet. Moreover, jailbreak creators are always a little late and hack the updated Apple operating system only after a few months. But in any case, they always manage to find vulnerabilities in it that can be successfully exploited for iOS 12.4 jailbreaking.
iOS 12.4 contains patches that close previously found vulnerabilities, including those that allowed jailbreaking for earlier versions of iOS. None of the existing jailbreak utilities are currently compatible with this update, and there is no one hundred percent guarantee that hackers will be able to jailbreak iOS 12.4.
As history shows, everything can be jailbroken, it's only a matter of time. If you want to enjoy tweaks on your device, you'd better stay on iOS 12.2 or the iOS 12.3 beta, but don't upgrade to iOS 12.3 or 12.4 release. Otherwise, you will have to wait a very long time for a compatible jailbreak and not the fact that you wait. Next jailbreak - iOS 13 Jailbreak. When? Nobody knows.
We once again strongly warn you that you can find links to download the Jailbreak iOS 12.4 on the web, but they are all fake. If you download and install these programs on your smartphones, the creators of these fake programs will have access to your personal information. We do not recommend installing them. You should understand that Jailbreak for iOS 12.4 and Jailbreak 12.3 does not exist yet.