Can a new iPhone sealed in box be banned from Snapchat?

Yes, if the phone is not really new......or......you are trying to log on using a user name and password that was banned on another device.

SnapChat knows more about you and your network than you might imagine.

Did you buy from an authorized Apple reseller? If yes, their name will appear when you use the link below to look for authorized resellers in your area.

Find Locations

Along with a device ban, Snapchat can also issue IP Address bans and Account bans that would affect any phone that you attempt to use. In all cases the issue would need to be resolved by SnapChat.

https://help.snapchat.com/hc/en-us

The "Using the Community" forum is for questions about the communities themselves. You'll be more likely to get useful advice if you post in the forum specifically for your device or operating system. As you work to become familiar with the Community, you may wish to bookmark this forum site map:

Site Map - Apple Community

That said, questions about using Snapchat would best be address to Snapchat support or posted in their user forums if they have them.

Regards.