Find a pretty girl, stand her in front of a scenic area and snap away! :smileysmileywink:
In all seriousness though, @Narces, if the Xperia XZ Premium does not have a "monochromatic" filter (it'll be in the camera settings, if there is such a setting), you will just need to find a third-party application in the Google Play Store... There's plenty of them out there.
Alternatively, you can take "normal" photos then add a monochromatic filter later, using a desktop program like The GIMP (or whichever image-editing program you prefer).
