If your feet required a "different" width you would know by this time in your life.

If your shoes wear out at the pinkie toe, you might have wide feet

If you find youself buying shoes with "lots of room in the toe" so they feel good, you might have wide feet

If your feet hurt at the pinkie toe after being in shoes all day, you might have wide feet [and have been wearing a shoe that was too small all day]

If you buy shoes a size [or 2 or 3] larger to make them feel comfortable, you might have wide feet

If you tie your shoes loose so the top of your feet doen't hurt, you might have high arches.

etc... you get the idea. Of course the antithesis is true if you have narrow feet. As you can tell I have "square feet" and a high arch. If I can find the width I can wear an 8.5, I usually end up in a 9.5 for the width and they still wear out at the outside of the toe box.

The cruciform shoe sizer that most shoe store use has a width measure as well