Best practice is usually to shoot in RAW and convert to black and white in post-processing, rather than relying on the camera’s built-in B&W mode. In-camera conversions often look flat because they give you limited control over contrast and tonal separation.

A useful workflow is:

• Shoot RAW so you keep all the color and tonal data.
• If your camera allows it, enable a B&W picture style/preview so the image on the rear screen shows a monochrome look while the RAW file still preserves full data.
• Choose scenes with a strong range of tones, from bright highlights to deep shadows, since black-and-white relies heavily on contrast and tonal variation.
• Convert later in software, where you can fine-tune contrast and simulate color filters for stronger B&W results.

So yes: the “trick” is less about a special camera setting and more about seeing in tones, exposing well, and doing the final conversion afterward.