Unless you read a book, that is a bestiary and that book mentions that entity, inspecting an enemy should require a very high DC- unless your tav is an inquisiter, loremaster or has a lore proficiency due to class picked. Eg:
Druid: knows most beasts, fey, Plants, and nymphs/ hags as they are opposing entities
Warlock: demons, others, ethereal
Paladin: devils, daemons, undead
Wizard / witch: elemental, celestial
Rogue / Fighter: orc, gnome, human, goblin
Hunter: giant, ooze, ogre, beast
Blood hunter: aberration, demon, fiend
Sorcerer: magic creatures, dragons, fey.
The above would be my recommendation. Mostly took it from my understanding of lore