In addition to the unc0ver jailbreak by Pwn20wnd, iOS 12 users have the option to use the Chimera jailbreak by the CoolStar-led Electra Team.
It’s worth noting that the Chimera jailbreak does not support Cydia or Cydia Substrate, and that it instead uses Sileo and libhooker as a part of its Procursus bootstrap for package management and tweak injection. That aside, it is the first public jailbreak tool to officially support A12(X) devices.