[Samsung Galaxy S8+ Questions & Answers] JeffDC:
I think you're asking if the periphery is out of focus?

Interesting question. Depth of field is the basic question, as I get it. What should be in focus, is based upon aperture (with correct speed: i.e. light). If I were trouble shooting an old camera, and checking the focus issue, I'd setup a field (stuff in the camera's focus range, at varying depths/distances from the camera), and take some photos in well lit conditions. It is important to know the 'depth of field' of a photo setting, so you can tell if the camera/lens and settings are all working as should be. The distance from the frontmost object, to the rear-most object still in focus, is called the 'depth of (the) field'

Check various distances/ranges from the objects, and see what comes out. If all is well there, I'd try different lighting variances, using the same distances as in step one.

Now, to test out the 'depth' portion of 'depth of field', you can set out a number of things, at varying distances, and given your 'depth of field' for your 'aperture', you should be able to see the things that are 'supposed' to be in the 'depth of field', all in focus. Remember, the smaller aperture, the smaller the hole that the light can pass through, the shorter, or less the 'depth of field', and the faster the shutter speed you can use (less light for a smaller hole). If you use a really large aperture, your camera will use a slower shutter/more light. If you go manual, which is a great way to learn how the camera 'depth of (the) field' works, you'll get a good understanding after a bit of time.

If the different distances and lighting comes out ok, both distance and lighting variances, I'd think you have a reasonable idea of the lens/camera portion is working correctly. The camera should take 'about' equally clear 'clarity', out to it's periphery.

If it's mux'ing up equally distanced (field of view) scenarios, I'd probably call Samsung. I advised well lit, so you can see what your are trying to investigate more clearly. using lighting variances would add to the 'evaluation' process, as that correlates more to a shutter speed.

You could go even further, by putting the camera into manual, and changing the aperture, test that out, and then the speed settings with varying arperture, testing that out . . .

but the basic 'auto' (auto aperture and auto speed) setting ought to work sufficient to get you the idea that yes, it is working/consistent/pretty clear at the periphery, or not. In very good cameras, with excellent lenses, the periphery is pretty spot on with the center of the lens, and that is with a great piece of glass. These cameras do a pretty good job, as well. Periphery is typically the more difficult ''depth of field'', as the lens, in some sense, is an approximation of your eye, with the higher definition in the center. Better lenses have a larger 'center' - some encompassing better to the periphery. Increasing the aperture increases the 'center' = greater 'depth', distance of the front most object that is in focus, to the objects behind a ways.

With the photos you posted up, it'd be necessary to know the aperture and speed being shot, to determine the depth of field (things that should be in focus based upon the aperture setting). Given the lighting, low/poor, a smaller aperture was likely used by the camera, with less/shorter depth of field.

Here is one example on how to calculate the 'field of view'.

http://shuttermuse.com/calculate-field-of-view-camera-lens/

There are hundreds of sites, but the calculation is basically about the same.

Also, if you could find someone near you with the same phone/camera, you could check their photos against yours, given the same parameters as above.

With your photos, above, if you were shooting (manual) with a hight speed, lets say, so less light coming into the lens, and small aperture, you'd have less 'depth of field', less things in focus. The larger the aperture, the more 'depth of field' you have. Speed needs to 'match', so you have the illumination good for the particular 'shot' you are wanting to accomplish. .So it's important to know the range, distance from the camera of the objects, to determining which ones 'should' be in focus, for the specific 'settings', i.e. aperture and speed (ISO) of film, or shutter speed, ASA..

I probably did not share this very eloquently, but I hope it gets across a few of the basic ideas?

Hope this helps.