Read The Economist , The New Yorker , or academic journals. You will see these C2 words "in the wild," which reinforces their meaning. Download Your C2 Level English Vocabulary List PDF
Switching between high-level academic prose and sophisticated wit. Category 1: Sophisticated Verbs (Actions with Nuance) C2 Level English Vocabulary List Pdf
When you learn a C2 word, find its B2/C1 equivalent. This helps you understand when to use the "fancier" version and when to keep it simple. Read The Economist , The New Yorker , or academic journals
To pronounce clearly or to state an idea in detail. Read The Economist