Bregxi iOS 12.3 Jailbreak repo extractor is released for all iOS 12.3 running device models. Bregxi comes with tons of awesome features.
Open Mobile Safari and install Bregxi from the above link.
Tap Get Repo and copy the Repo URL.
Tap Extract Repo to open it.
Enter Repo URL and tao Ok button to extract.
Now you can install jailbreak apps and tweaks using Bregxi.