I tend to have NPC peers of the PCs be in the same kind of realm of power - low mid or high.
Low level PCs hang around villages, the village elder is 3rd level.
Mid level PCs operate at a regional level, the local baron is 8th level.
High level PCs operate at an international level, the king is 12th level.
Very powerful very high level PCs are still dealing with kings, but also possibly with legendary rulers like Caesar or Alexander, these Imperial rulers may be say 16th level+ if they carved out their empires by their own hand.
Low level PCs hang around villages, the village elder is 3rd level.
Mid level PCs operate at a regional level, the local baron is 8th level.
High level PCs operate at an international level, the king is 12th level.
Very powerful very high level PCs are still dealing with kings, but also possibly with legendary rulers like Caesar or Alexander, these Imperial rulers may be say 16th level+ if they carved out their empires by their own hand.