What is the supplied power when a USB-C device is connected to these Macs, such as connecting an iPhone 7 Plus with a USB-C to Lightning cable. I know the iPhone 7 Plus can take 1.8 to 2.0 A in tests I did. Any help much appreciated.
Semantics I know but to make it clear..
USB-C does not delivers (produces) power, it only carries it from one end to another.
The USB-C can carry 20 Volt and 5 Amp (100 watts).
The supplied power will depend on the device type (the consumer) and the source output (the supplier).
In case of iPhone 7, it needs 5 watt (5 Volt and 1 Amp).