To do that, you need:
The Goethe-Institut provides manuals that describe the exam's linguistic goals and standard topics, which help define the expected vocabulary range. Goethe-Zertifikat C1 Handbuch i goethe zertifikat c1 wortliste pdf link
This page offers free sample exams (PDFs) which contain the vocabulary in context. To do that, you need: The Goethe-Institut provides
To prepare effectively, you should look for resources that categorize vocabulary by theme (Umwelt, Wirtschaft, Technologie) rather than just alphabetical order. To do that