Can you buy a Refurbished iPhone from T-Mobile?

If I obtain an refurbished, unlocked iPhone 14 (for my daughter), I can:

1. backup her phone to the iCloud
2. move the SIMM card to her newer iPhone 14
3. restore her iPhone 14 from the cloud

My questions are:

• how do I ‘update’ the type of phone for her phone number on My TMobile account?
• is there anything I need her to do at a T-Mobile store?…
• although not purchased via T-Mobile would T-Mobile help her with the phone or account?
• could a protection plan be bought through T-Mobile for that phone although not purchased through T-Mobile?

Thanks.

The refurbs that T-Mobile has are usually at Assurant and are used for warranty replacement.

Try Amazon, Apple or eBay for a refurbished phone.