Arguably the most common full-frame equivalent focal lengths used in street photography are 35mm and 50mm. Both focal lengths are extremely versatile and great for capturing a scene or moment in anyone’s day to day. As a previous fan of using 50mm for street photography, I have come to really enjoy using a telephoto lens for street photography, more specifically, an 85mm.
Using a short/medium telephoto lens like an 85mm has let me take on a style of street shooting where I focus and give significance to more nuanced details in a moment like the expression someone has on their face.
Since telephotos pull in backgrounds, it provides the opportunity to pick and choose exactly what you would like to include into your backgrounds much more easily than a wider focal length would. A huge benefit for an 85mm lens specifically, is that despite being a telephoto lens, which tend to be larger, 85mm lenses are generally smaller than other telephotos due to their design, meaning it is much easier to be stealthy while out getting street photos.
Admittedly, you might find yourself having to step back to fit what you would like into a frame, but it is a small downside for the kind of results you will get when implementing a narrower focal length into street photography.