which lens & aperture was used to achieve this image? or what could be used to do so?

I’m curious to know how the lack of focus was achieved in the image. My presumption is a 50mm lens shot at an aperture of f/1.8?

Also for reference i use a nikon dslr with a cropped sensor, so my focal length is timed by 1.5 (for example to get the look of a 50mm lens, id by looking for something 32-35mm instead).