To design a GUI (Graphical User Interface) that supports both small group meetings and large webinars, consider the following:

1. Scalability: Design a flexible layout that adapts to different group sizes.

2. Customizable layouts: Offer various layouts for different use cases (e.g., small groups, webinars).

3. Participant management: Include tools for managing large numbers of participants.

4. Role-based permissions: Assign different roles (e.g., presenter, moderator, attendee) with varying permissions.

5. Breakout rooms: Allow for virtual breakout rooms for smaller group discussions.

6. Screen sharing and collaboration: Support multiple presenters and collaboration tools.

7. Audio and video settings: Provide options for optimizing audio and video quality.

8. Chat and Q&A: Include chat and Q&A features for attendee participation.

9. Polling and surveys: Offer polling and survey tools for engagement.

10. Recording and playback: Allow for recording and playback of meetings and webinars.

11. User profiles: Enable users to create profiles for easy identification.

12. Accessibility features: Incorporate accessibility features for inclusivity.

13. Mobile optimization: Ensure a seamless experience across devices.

14. Clear typography and color scheme: Use a clear and visually appealing design.

15. User testing: Conduct user testing to ensure the GUI meets diverse needs.

By incorporating these features, you can create a GUI that effectively supports both small group meetings and large webinars, providing a flexible and user-friendly experience for various use cases.