We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
With age, gravity tends to give us a larger foot size. Our feet expand under our weight.
I have a couple of pairs of expensive (well, expensive for me) and highly-durable Brooks Brothers loafers which I am loathe to part with but are no longer comfortable. 20 years can do that. Mrs. BD says I am silly not to replace them, but I tried some tricks of the trade first. It is not unusual to be like me, with feet of slightly different sizes but who will not spend the money for custom shoes in London.
Solid, well-made leather shoes can be stretched between a half-size to a whole size. Inexpensive shoes can not take the stress of stretching - either the leather itself, or the stitching, will break.
Things to try:
Shoe stretchers will adjust width or length. Cheap on Amazon. Over a day or two, you keep increasing the tension in the stretcher. Heating the shoes with a hair dryer or in a hot sun makes the leather a bit more stretchable.
Wetting the shoe well with water or, better, isopropyl alcohol (rubbing alcohol) before stretching is what expert cobblers do.
Simpler, soak some heavy socks with water or rubbing alcohol and wear the shoes. If sitting, it should be painless.
Results of my experiments with these? Be careful not to overdo it or you can end up with loose shoes.
Many years ago while living in the desert I bought a pair of high boots, kinda like cowboy boots but without the pointed toe. Sadly they were not comfortable and I got blisters wearing them. Someone advised me to soak them and then to wear them until they were dry. I filed each of them with warm water for half an hour. Dumped out the water and put them on and wore them all day. After that they fit beautifully. I wish I still had them. Good protection for walking in the desert and just all around comfortable. Since then I have heard people say don't do that it will ruin your shoes but it didn't and I can see no reason to think it would.
I have a nice pair of leather hiking/work boats that even after a year were stiff and uncomfortable. I wore them on a hike up the Virgin River and back and then wore them the rest of the day. Since then they have become my favorite boots.
My first experience with this method occurred during my time at NOLS, forty some years ago.
Everybody who didn't already have boots, bought a pair of (Pivettas) which were stiff as could be. We were then led to a large trough of warm water, where we were told to enter the trough and stay there for 15 minutes and walk in place. We then wore the boots until nightfall.
Damn things fit like a glove for ever after. They just gave up the ghost about three years ago and I'm loath to throw them out.
Pregnancy also affects the ligaments and some women go up a shoe size.
For about a year after I broke my leg, my right foot was a 1/2-1 size bigger, which doesn't make alot of sense, since my ligaments and tendons shrunk from being couch-bound for almost 4 months.