If my contract is done and I upgrade to a new iphone, would this mean that my old iphone 5s is considered "unlocked" and can be used with any carrier? Just trying to figure this out before I sell it.
No. If your carrier offers unlocking, you must contact them and request that they unlock it.
See this document: How to unlock your iPhone - Apple Support
No. Your contract status has no relation to your phone being locked or unlocked.
Some carriers may automatically unlock the iPhone one the contracts completed, but this is not generally true for most carriers.
If you want to unlock it, you can contact your carrier and request they unlock it. They'll generally do this for free if you meet their requirements for unlocking.
Apart from getting it unlocked (some carriers will NOT do it), be sure to do this before selling: What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support
iphone 5s unlocked?
