Contrasting a high magic society to the rest of a setting

[Prime32]

Ireland

I’d like to strike them with a sense of Different and Fantastic that calls back to the wonders of childhood discovery.

The party need to travel to get there, so some of the old stories of sea journeys might offer inspiration - Wikipedia has pages for The Voyage of Bran, Máel Dúin and Echtra Cormaic. One scene in particular that could set the tone:

After two days, he sees a man on a chariot speeding towards him. The man is Manannán mac Lir, and he tells Bran that he is not sailing upon the ocean, but upon a flowery plain. He also reveals to Bran that there are many men riding in chariots, but that they are invisible.