Fashion and portrait photographer Richard Avedon produced a legendary body of black-and-white work, much of which involved isolating subjects against a pure, shadowless white backdrop.
He shot many of his photos in a studio, where assistants would carefully position large studio lights. Search this technique online and you will find scores of articles and videos on how to light both subject and background for the Avedon look.
The iPhone now lets you do this with a single finger tap, thanks to Portrait mode advances.