Buy a leather conditioner, let it dry, and wear around the house, repeat, it sounds goofy that you would have to wear them around the house but it works. I have also heard of a “stretching liquid” that you can buy from shoe stores but I have never tried it- apparently when you use that you also have to get a metal/wooden shoe stretcher to insert into the boot. Be careful not to stretch too much. I hope this helps, it is always a pain when you buy boots and they don’t fit.