I am using an Android Oreo phone. I would like to make a video of myself, but while I make it, I want the screen to go blank. This is so that looking at myself on the phone while I record will not interfere with how I end up appearing on the video. This way I can also think about how I would look at another person while I pull the face in thinking about, and then see for myself what my face looks like, so as to be able to foresee how I come across and what I can guess the other person's reaction would be, as seen by reacting myself to myself.
Any suggestions on how to go about doing this?