The agreement with Asurion is a certified refurbished phone, never a new phone.

Does Asurion send new or refurbished iphones?

Once the insurance claim is approved you'll be told if Asurion is electing to repair or replace the device— and you don't get to have any say. If it's the latter, they'll ship it out to you overnight. A phone charger, battery, and a SIM card will be included. It may be new, or it may be refurbished.

Can I upgrade my phone with Asurion?

It is entirely normal for Asurion to replace a phone they don't have, with a phone they do have, in this case, a newer phone with better specs. They do not charge extra for this..