If the very good battery life of the current iPhone 11 series is not enough for you, you can now buy the official battery cases from Apple.
For the models mentioned, there is now a matching battery case in several colours available for just under $130. The battery capacity is so large that you get 50% more battery life than with the iPhone alone. The price is quite high – at least this generation has built in an extra button with which the camera app can be called directly.
If you want to extend your battery life but don’t want to spend so much money, look at Amazon for cheaper alternatives. These may then do without wireless charging, but sometimes only cost a fraction of Apple’s models.