To understand the trade-offs, here are some basics:
Focal length:
A lens casts an image of an object in front of the lens to a sensor (or film) behind the lens. Let's call the distances between lens and sensor Dsensor, and the distance between lens and the object Dobject.
When the object is very far away (say, the moon), Dobject is very very large (practically infinity). Where that image is sharply cast (Dsensor) is the focal length of that lens. While this is not the technical definition, this is the practical effect. So, if a particular lens casts the image of the moon (objects at infinity) sharply at 50mm, you have a lens of 50mm focal length.
Most camera lens are really composites of a few lenses each doing a particular job to get the best effect. Some composite lens are zooms - a lens with variable focal length.
Depth of Field:
Depth of field is the range within which the image stays in focus. As you can imagine, when the moon is in focus for that 50mm lens, a guy standing 100 miles away is in focus also. Say as the man walk closer and closer, he stayed in focus with the moon until 50 feet away. So in this scenario, image stayed in focus (at that setting) from a range of 50-feet to infinity (~240 thousand miles). This range - the range where an image stays in focus is the depth of field. The bigger the focal length, the smaller (shallower) the depth of field.
As the man walk closer, the depth of field reduces. The closer the object, the shallower the depth of field.
Aperture:
Now imagine if you borrowed a good (big lens) astronomical telescope say in the 1 to 3 meter focal length range... Probably, when the moon is in focus, the man 50 feet away would be out of focus. Ironically, a cheaper one (small lens) could put both the man 50 feet away and the moon both in focus. The bigger the lens opening (aperture), the shallower the depth of field.
With astronomical telescopes, you typically do not have aperture control. It is always open to the max. With regular (real) camera, you typically have aperture control - the so called f-stop rather like a mechanical eye-pupil to reduce the size of the opening. The larger the f-stop number, the smaller the opening. So, one can increase the f-stop to simultaneously reduce the amount of light going in and increase the depth of field. You can't just get one effect, you get both effects.
As you can image, it is hard to make good big lens. So, a lens with f-stop range f2.8 to f16 would be a good bit more expensive than a lens with similar quality but with f-stop range f5.6 to f16.
Smart phone camera:
Typically, smart phones are thin. The camera would likely have a very short focal length. A 50mm lens (standard lens for a 35mm camera) would cast the image of the moon 50mm from the lens. To have a sensor that far from the lens would make your cell phone the size of a brick.
Smart phones' thinness limits the camera lens to very short focal length. Short focal length would have great depth of field, but the image cast on the film/sensor would be smaller - resolution would not be as good as a lens with longer focal length. Note I am assuming the CCD sensor is sized to the image. Larger sensor would increase cost.
Smartphones (and many digital cameras) use digital zoom instead of optical zoom. Optical zoom is the lens-glass doing the focal length adjustment. Digital zoom just crops an area of the sensor and then enlarge that area digitally to full size. Since you are cropping out some of the pixels in your sensor, you are loosing resolution. Say if the un-zoomed image of a screw is too small and you digitally zoom in to make the screw twice as long, you would be using just 1/4 of the pixels of the sensor. Smartphone with optical zoom is rare. The only smartphones I know of with optical zoom are the iPhone X and the ASUS Zenphone 3 Zoom.
To reduce cost, many smart phones doesn't have real aperture control. Instead, the amount of light is controlled by shutter speed (length of exposure). In fact, you would have very limited choice of smart phone if you want real aperture control. Glaxy S9 is the only one I know of with some actual aperture control.
I hope this helps with your trade-off decisions.