When setting up the new IPhone, does it have to be fully charged?

If you’re switching from an old phone and are going to transfer information, no. I think 50% should be enough.

If it were me, I would just plug it in and do the set up as a precaution. 50% should be enough, but if you have convenient access to power, plug it in.

~Lyssa

Here’s what I found to answer your question:

https://support.apple.com/en-us/HT208387?cid=iOS_SettingsUI_iphone_article_HT208387

See Wise_Mouse's response for more info. But, it is no longer necessary to fully discharge the battery when you get a new device. Just start using it.

~Lyssa