When the lens aperture is wide open and your subject is close to the camera and the background is far away, you get a nice soft background , nice bokeh.
Bokeh is better with some lenses than with others. Some of that is to do with the lens elements in the lens itself. Some of it is to do with the maximum aperture, and some of it is to do with the size of the sensor in the camera.
For the best bokeh you want a lens that can open really wide. An aperture of f1.4 would be great, but those lenses are expensive. Many budget cameras such as the Nikon Dxxxx range have nice budget lenses with f1.8 aperture. That’s a good budget option.
Next you want to choose a focal length that allows you to put the subject a bit further back. If you take portraits you don’t want your friend’s face smack up against the lens – it will make them look like a sheep. A 50mm f1.8 lens is cheap and sharp.
Shoot it wide open at f1.8 and you will get good bokeh. See, I didn’t talk much about cameras it’s the lens and the sensor size that makes the good bokeh, like the sensor on the Nikon APS-C sensors on the Dxxxx range. Canon make a similar range and so do Fuji.
You could go for Panasonic or Olympus, but their micro 4/3 sensors are a bit smaller, so with the exact same settings, bokeh won’t be quite as good.
The tiny sensors you find in phones means will have a greater depth of focus, meaning more is in focus front to back. That’s not a bad option, but if you want good bokeh with a phone you have to put the subject very close to the lens and the background a long way off. Otherwise, everything front to back will be in focus and you won’t get any bokeh.