The LG G7 ThinQ is a Qualcomm Quick Charge 4+ enabled phone supporting USB Power Delivery 3.0, PPS (Programmable Power Supply), and Qualcomm Quick Charge 3.0 technology over USB Type-C which also comes with dual-role power capabilities. This conveniently lets you use the LG G7 ThinQ to charge other compatible devices such as the Apple 12.9-inch iPad Pro when there's no AC power available as well as being able to be charged itself.
Given the Apple iPhone and iPad Pro's that support USB Power Delivery can only consume and not supply power, the LG G7 ThinQ will be acting as a power bank to the Apple 12.9-inch iPad Pro, while consuming the phone's own battery charge to support charging the iPad. Thus, the LG G7 ThinQ needs to have sufficient amount of battery charge for charging to run smoothly.
When connected over the Apple USB-C to Lightning Cable, we observe how the LG G7 ThinQ at 91% battery level supplies power to a 12% charged battery on the Apple 12.9-inch iPad Pro using USB Power Delivery. Make sure to select 'Charge connected device' from the LG phone's USB charging options. The iPad Pro when connected automatically just supports charging in.
The LG G7 ThinQ from initial plugin could be seen to supply about 7.5 watts of steady state charging to the Apple 12.9-inch iPad Pro (which results in slow charging for the iPad given its big battery). Click here to download the trace captured by the GRL-A1 power analyzer to see more details. Although 7.5 watts leans more towards the USB Battery Charging 1.2 spec rather than USB Power Delivery and the iPad Pro can charge much faster using its own 12W based charger, certain Android phones like the LG G7 ThinQ is still useful to charge up the iPad Pro when there's no access to AC power source.