The amount of optical background (or foreground) blur is controlled by several parameters:
- Focal length: longer focal lengths give more background blur, shorter focal lengths less
- Aperture: wide open shots give more background blur, stopped down shots give less background blur
- Sensor size: bigger sensors give more background blur if effective focal length stays the same (having the same field of view -- not the same as physical focal length staying the same) and if aperture F-number stays the same, smaller sensors give less blur in these circumstances
- Subject distance: macro shots (shots of something nearby) give more background blur, shots of something further away give less background blur
I'm sorry to say your Pixel 6 can't take the photos you want. A smartphone camera has a fixed aperture and it's usually relatively wide (something like f/1.8). The focal length is usually normal, not superwide, not tele. Sensor size is small, but do keep in mind that the small sensor size works to reduce background blur whereas the wide aperture works to increase background blur. So the small sensor doesn't give you an entirely background blur free image. Additionally, for a smartphone the Pixel 6 sensor is extraordinarily large.
What you can adjust is the subject distance. Move the food further away from the camera (or the camera further away from the food), and you reduce the blur.
However, this may not give you the composition you want.
Background blur is:
b = f*m_s / N * x_d / (s ± x_d)
where f is focal length, m_s is subject magnification (e.g. 2 meter human is 24mm on sensor => magnification 24/2000 = 0.012), N is aperture F-number, x_d is distance between subject and background, and s is subject distance.
You can combine (1) and (2) by considering aperture size in millimeters (f/N in the formula). So for example 5mm f/1.8 is 2.8mm. It gives a certain blur disc size. However, that blur disc size is a certain fraction of the sensor size. With a smaller sensor (where 5mm gives a narrower field of view), the blur disc size stays constant so there's more blur. However, on a smaller sensor you would use a shorter focal length, let's say 2.5mm, where 2.5mm/1.8 would be 1.4mm. Also the shorter focal length would have different subject magnification (half of the magnification). So you cut blur disc size into one fourth, and cut sensor size to one half, so the blur disc size divided by sensor size is half of what it used to be.
On Pixel 6, you you have 12.2mm sensor diagonal, f/1.9 and 26mm equivalent focal length. The crop factor is 3.5 (calculated from pixel size and count, may be slightly inaccurate, assuming 4/3 aspect ratio which might not be correct). So you have 7.4mm physical focal length and f/1.9. That's aperture opening of 3.9mm, compared to sensor diagonal of 12.2mm or aperture 32% of sensor diagonal.
A professional photographer would grab a full frame camera, pick a 24-70mm lens zoomed to 26mm, say "screw diffraction", set aperture at f/22, turn image stabilization on and use a long exposure time, maybe a very little bit fill flash with a flashgun if the lighting requires it. Then the aperture would be 26mm/22 = 1.18mm compared to sensor diagonal 43.3mm or aperture 2.7% of sensor diagonal. However, 3.5 times bigger subject magnification with a full frame camera mean the comparable number is 3.5*2.7% = 9.45% compared to 32% of Pixel 6.
Pixel 6 is useful for low light shooting with something that fits into your pocket. Pixel 6 isn't the proper camera for the photos you want to take. For food photography with sharp background, you don't want to use Pixel 6. You want to use a camera with a lens that has adjustable aperture and image stabilization.
Also, many phone cameras these days have a portrait mode in which background blur is simulated. In this case, it isn't a real optical effect. You can turn the effect off in the camera app. For the picture of your friend 5 meters away, this could be the cause.
