Do templates (for monsters) exist in 2e?

[Yqatuba]

If so, where it the book are they listed?

[Gorbacz]

Yes, in Bestiaries, for example: Graveknight.

[Castilliano]

Note that in the template descriptions often Paizo advises building a monster from scratch instead. The template can be used for quick adjustments, or to garner ideas or core traits from.

The monster-building guidelines are user-friendly.
You can move stats up from "high for level X" to "high for level X+1" alongside adding some features, i.e. Regeneration on a half-Troll.
If you have the Bestiary & GMG open side-by-side, it's a lot easier than it sounds.

[Paradozen]

Also the Gamemastery Guide has Trait Abilities you could add to a creature to imitate some 1e templates like Fiendish or Celestial

[masda_gib]

Also the Lost Omens World Guide has templates for different factions that you can apply to monsters. If you want to make a Orc Hellknight or a Troll Pathfinder.