I called several times, they told me yes before I got the phone.
Trying to currently change it, the lady said it was possible — but told me the phone amount (1,249) would be applied to the bill.. and a dispute would have to take place and it can take months before I get my line reactivated. She said she wouldn’t recommend it cause it can be detrimental to my account and a big hassle.
I accidentally picked next 30 instead of 24 myself when I preordered. Went to the store on Friday and they switched the plan for me after activating my phone. It was super easy and then I had to reactivate my phone by accepting the new terms for 24 months. It can be done in store.