Yep, some are a little more basic than others, but they gave me a framework to quickly alter a creature. What I was using is below.Are these templates you can apply to existing 5e monsters? Like a skirmisher owlbear?
There are a few things that reference it, but they use the term half maximum hit points or something to that effect. Things like the champions regeneration or the life clerics channel divinity are capped at what could have been easily tagged as the bloodied condition.The bloodied condition is quasi-official in 5e, since the description about hit points describes it explicitly.
It has no mechanics on its own, but is important in narrative adjudication, such as when using the Intimidation skill to force surrender.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.