You Need an iPhone 8 or Newer
Apple enabled wireless charging for its iPhones starting with the iPhone 8. So you will need an iPhone 8 or newer for wireless charging to work, otherwise, it just can’t happen.
Also keep in mind that software also plays an important role in regulating how your iPhone charges. If you have a compatible iPhone, make sure that your iOS is updated to the most recent version as well. The latest iOS versions support wireless charging up to 7.5 watts. This isn’t as high as some other smartphone brands, but plenty of power to safely and quickly charge your iPhone.