im sure it varies shop to shop how chill they are and therefore if theyre willing to bend them for you
won't hurt to ask. i hate messing around with my bindings so ive always asked the shop to do it when i needed it.
if they won't, id look online to see how to do it because it's not complex, it's just a little bit of a pain. i think the most popular method is to use a ski pole or (maybe more rigid) hollow pipe to slide over the brake, and use its leverage to bend it out. a 90mm brake on a 100mm ski means youre only bending each side like 5mm, so not really a huge deal. i think the last pair of brakes i bent were somewhere in the 70s or 80s and i bent them for a 95mm waist