Lobotomy Mod
Lobotomy Mod 1.12.2 adds an item, the Lobotomy Tools, which may be used by right clicking to make a hostile mob passive. Just a little tap on the monster while holding the tools, and they will become meek as a villager, and be completely defused. They may even decide to follow you around, but never again will they attack another living creature.
Be careful, though. If a monster is part way through its attack when you lobotomy it, for example a creeper priming to explode, it will follow through. Think of it as an added layer of risk.
Screenshots:
Two Lobotomized Creepers
Requires:
How to install:
How To Download & Install Mods with Minecraft Forge
How To Download & Install Fabric Mods