There are new rules regarding when carriers must unlock devices for you. Although policies still vary by carrier. Verizon says they don't lock most 4G devices and freely provide unlock codes for the few that are. There is a pretty comprehensive article with links to the various carrier policies here:
http://www.computerworld.com/article/2883411/new-rules-how-to-unlock-your-smartphone.html

Once unlocked, IF the phone frequency matches local service, you can get a local sim and put it into your phone. As mentioned, not all phones are capable of being a hot spot, though many are.