Can sprint unlock my iPhone 7 yes or no?

If it is currently locked to sprint then yes they can

As long as you buy the phone from Sprint yes.

As long as the phone is paid for, yes.

If you owe more than half of the Sprint retail price on the phone, no.

If the phone is question has been reported lost or stolen, no.

Sprint makes it very confusing; some will tell you yes, while others will tell you no.
Go here: https://support.sprint.com/support/article/FAQs_about_unlocking_your_Sprint_device/7a3bf815-cfcd-4a56-925a-7a187d1c6637