Option to turn on/off fast charging while charging your phone

[pmel]

Now I've discovered the possibility that I can turn on/off fast, super fast and fast wireless charging when my phone is charging. This option on OneUI3.0 was impossible, I had to unplug the cable first. Maybe I'm wrong, if so, please correct me. 

Edit 18:25

While charging, you cannot activate or deactivate the Fast charging or Super fast charging feature.

Source: https://www.samsung.com/uk/support/mobile-devices/how-to-use-and-charge-galaxy-s21-series/

[rikob1]

Yes, I also turned off the quick charge option while charging the phone.