The Sandberg Wireless Charger Pad (15 W) is compatible with iPhones, specifically those that support Qi wireless charging, such as iPhone 8 and later models.
Please check whether your power supply unit can output 5V/3A. This should be indicated on the power supply unit in the small print under OUTPUT.
Older power supplies may not be suitable.
I don't have either of the two smartphones, but I think it is difficult to make an exact statement here, because all modern devices do not charge the battery linearly. In addition to the condition of your battery, the current charge level and time of day play a role. The charging curve is usually degressive, i.e. the battery is charged heavily at the beginning and then less and less in order to conserve the battery. Overnight, the battery is often only fully charged in the morning hours to be particularly gentle.