I always prefer to wear well-fitting Red Wings and other heavy leather work boots, both lace up and pull on. Too tight when new that would eventually fit like socks. Oiling, waxing, mink oil, etc. it was usually a painful process process until they finally fit right. Then, one of the shops that resoled several of my boots taught me this-
Using a hair dryer or heat gun (low temp), heat the areas needing stretching to soften leather. Vigorously work & stretch the warmed areas over the smooth rounded end of a wooden broom handle or similar, held between your legs or in a vise. Make sure the rounded handle is smooth so it doesn't tear the inner lining of the boot or shoe. Really go to work, use your body weight and stretch the offending areas. This works for clearancing for high or tall arches, bunions, crooked toes, etc. it's simple to stretch specific areas without disrupting others that fit well.
He also advised me to use the same heat gun or hair dryer to expedite oiling or waxing the leather instead of the old method of wipe-on application, waiting overnight or longer until it is absorbed & repeat until no more is absorbed.. Heat the leather, apply the product of choice and watch it disappear into the warm leather like a sponge absorbs water. When it stops absorbing, wipe off excess and you're done. It works great for all leather products- boots, gloves, jackets. I like sno seal (no need for a mink oil vs wax vs whatever debate) and apply completely like this as soon as a new item comes home with me. It takes a few minutes to completely prep your boots instead of a few days.
Doing these two thing together for new boots will help shorten the break-in time from weeks or months to an afternoon. He said that's how he was trained to do it and had been doing customers' boots and shoes like this for decades.