Does game designing require programming knowledge?

No. Game design is about scripting things in a game. But, knowing programming can be beneficial as it:

Helps understand the systems and mechanics of games in detail.

Helps communicate with programmers & convey ideas in a better way.

Helps improve the portfolio.

So, having knowledge in object-oriented programming languages like C++, which is used for rendering engines, heavy computations, providing advanced networking capabilities for real-time multiplayer interactions and C#, which integrates seamlessly with the Unity game engine and also used to develop cross-platform compatibility games, can leverage your strengths and help you land a job in this booming industry.