If wifi is on then wifi direct is also available.
This may be the case with more current versions of Android, but not all. I have two Samsung devices. One runs Android v-4.1.2, while the other v-4.0.4. Version 4.1.2 handles WIFI Direct as you say. But version 4.0.4 requires that a WIFI Direct slider, in wifi settings, be manually set to on. When this is done WIFI Client/Hotspot is then turned off.
I have found using WIFI Direct between these two devices to be quite flaky. Sometimes connections and file transfers are made with ease. At other times it’s impossible to make a connection at all. There is another problem I have found with v-4.0.4, in that it is impossible to use USB Debugging. The USB connection is made, but B4A cannot connect for debugging as no connected device is detected.
I think I will have to put this project on the back burner, until I replace the v-4.0.4 device with something newer.
Best regards