I would try on a pair of whatever model you might want to buy. I think the UltraBoosts arre relatively normal, but they have somewhat stretchy uppers, so maybe it's a bit deceptive. If the bottoms of your feet are flat/wide, you might feel they run a bit narrow, I looked at the insert and the sculpting around the arches, and maybe these will be tight on you. You can also try going up a size, the shoes wear "tight enough" for your foot not to slide.
These Boosts, and a couple of other models I've tried, have plastic stripes on either side that provide a bit of side-to-side support. The stripes are only connected by the laces, so depending on the size of your foot (both width and height), they can expand or contract based on how you lace them.