大智若愚 (dà zhì ruò yú): A person of great wisdom often appears simple or even foolish on the surface — Meaning & Stroke Order

In the workplace, people who appear foolish but are truly wise often go further.

Don't judge by his low-key demeanor; in fact, he is a case of great wisdom appearing foolish.

This old professor dresses simply and speaks plainly, but his knowledge is profound. He can be described as 'great wisdom appears foolish'.

In 'Romance of the Three Kingdoms', Zhuge Liang often appears as someone with great wisdom appearing foolish.