Bring your own phone promos are typically for new activations.  Are you a current customer?

I’m not a current customer, but will become one. 

Then yes you can order a BYOD plan  and select a phone and pay the full price.

Note that wireless carriers all inflate their phone prices to encourage customers to buy their phones on tabs with sale promos which entrap customers in.  So when customers want to leave, they need to pay the sales promo back (like a penalty for cancelling a contract).

You may want to buy your phone direct from the manufacturer.