Here you can find confirmed Unc0ver Jailbreak Download Links to iOS 12.1.2 Jailbreak on iPhone, iPad and iPod Touch running on iOS 12.1.2.

Unc0ver Jailbreak tool – Pwn20wnd, a former member of the
Electra team, has released an updated tool Unc0ver – version 3.0.0 With
it, you can make jailbreak devices running on iOS from version 12.1.2.

UnC0ver
supports the same iOS versions and the same devices as the Electra
jailbreak and automatically installs the Cydia tweak store on the hacked
device. The main difference from the Electra utility is that Unc0ver
uses Cydia Substrate to install tweaks not the Substitute, but the Cydia
Substrate.

Updated. Jailbreak creator having the name Pwn20wnd, has released an updated version of Unc0ver jailbreak utilities for jailbreak Apple devices that run on iOS 12.x.

Unc0ver iOS 12 Jailbreak Download Links

— Download links (iOS 12.1.1, iOS 12.1.2)

Unc0ver iOS 11 Jailbreak Download Links  

— Download links (iOS 11, iOS 11.1, iOS 11.2. iOS 11.3, iOS 11.4 beta)