Under Sprint’s unlock policy, the phone has to have been activated for a minimum of 50 days on the Sprint network, be completely paid off, and be under an account in good standing. If the phone was never activated on Sprint network, then no it cannot be unlocked.
I bought a Sprint iPhone 8 and learned the hard way. The seller said it was unlocked for Sprint and Boost. I should have been suspicious then. The Sprint iPhone 8 is GSM compatible and uses a nano SIM and therefore should work on any major wireless carrier including t-mobile and AT&T. I learned the hard way that despite the phone being fully paid off, it still required 50 days on the Sprint Network (AT&T and T-Mobile also require similar for unlocks). So I was lucky to add a...