At about 20 years of age the bones of the feet stop growing,perhaps a little earlier in women.
That is the bones, however during life there will be a change in shape and also a change in size, due to age related disaeses e.g osteo arthritis and the formation of abnormalities such as Gout and Bunions.
I was told by someone in a shoe shop that as you get older the arches in your feet drop, therefore making you up to one shoe size bigger as your feet become flatter and longer.
A lot depends on the fitting. I used to be a standard size 6. Then about 30 yrs. ago the sizes seemed to change and I was told that manufacturers were responding to people being bigger. I don't know if that's true or not. Anyway, I suddenly became a size 7. Trying to buy cheap shoes means 8s usually don't fit - either too big or too small.
I definitely feel that my feet are wider and so I had them measured - size 6-and-a-half EE fitting. I've 2 pairs like that & they're comfy - except a bit short for a long 2nd toe! I give up!