Be aware that the World Travel adapter kit only replaces the plug section (prongs that plug into the wall outlet) of Apple power adapters that have a removable plug section (commonly called duckhead).
See the following from Using Apple power adapters, cables, and duckheads with Apple products - Apple Support with red outline added by me near the black line where the duckhead joins with the rest of the power adapter.
Many power adapters such as the Apple 20 watt USB-C adapter commonly used with iPhones do not have a removable duckhead and will not work with the World Travel Adapter kit. See: Apple 12W USB Power Adapter - Apple
Those power adapters that do have a removable duckhead will only be able to charge the same number of devices with the power adapter as they could with the original duckhead.
If you are looking for a travel adapter for an Apple power adapter that doesn't have a removable duckhead, they are available from many sources such as the following from Amazon. Some of them you would plug your Apple 20 watt power adapter into and some of them have USB-C ports that you could use without your Apple power adapter. See: https://www.amazon.com/italy-power-adapter/s?k=italy+power+adapter