I have an iPhone 7 Plus. I need a wireless charger. Is there one safe for my phone?

The iPhone 7, or 7 Plus don't support wireless charging. This feature was only introduced in the iPhone 8, and 8 Plus.

The only way to get wireless charging on an iPhone 7+ would be via a wireless charging case. That would connect to the Lightning port and then will charge when connected to a wireless charging pad. With that, any Qi-compatible charging pad should be fine.

Your iPhone does not support wireless charging.