How do you achieve this look:
Create the Background color and the Main Image layer. Click the Main Image layer thumbnail holding Cmd Mac or Ctrl Win to load the transparency selection and copy it.
Make a Fill Color layer
Click the Fill Color layer mask holding Alt to see its content
With the selection active, paste
Cmd + I Mac or Ctrl + I Win to invert. Click the Color Fill thumbnail and hid the Main Image layer.
Click the mask and apply levels: reduce midtones increasing shadows and highlights
Original image from unsplash.com