Average sized 1″ (13.2 x 8.8 mm) sensor
Even though Sony RX100 IV's sensor is significantly larger than a typical compact camera sensor, it is still hard to achieve that shallow depth of field and a blurry background for your portrait shots. Very High Resolution Sensor: 20.0MP
Sony RX100 IV's 20.0MP sensor will provide larger room for cropping, and you will be able print your portrait shots larger with more fine detail. Image Stabilization
Image stabilization reduces the effects of camera shake at long exposures and long focal lengths thus ensuring sharper portraits RAW shooting capability
RAW files contains more color information compared to JPEGs, so it is easier to get a natural skin tone and colours during post processing, which is very important for portraits. Electronic Built-in Viewfinder
During a portrait shoot, using a viewfinder allows the photographer to stabilize the camera and reduce the camera shake since it is closer to the body. Besides, it comes handy where LCD screens are very hard to read under bright sunlight. Manual Focus Mode
You have to nail the focus perfectly for a good portrait shot. Compact cameras are not great at focusing at low light and complex lighting conditions, so manual focus mode is very useful at these times. Manual Exposure Mode
A correct exposure of portrait model is crucial. Even though modern digital cameras features advanced algorithms to calculate the right exposure, they still may fail some difficult conditions. Manual exposure mode in these conditions helps a lot in order to achieve correct exposure.
No External Flash Shoe
Use of External flash creates many creative lighting opportunities for portrait photography and built-in flashes are almost useless for portrait shots. Not so good Ergonomics&Handling
Good handling and existence of well placed physical controls on the camera body is very important during portrait shooting. It is faster and more intuitive to change the camera settings with dedicated buttons and knobs instead delving into the menus on the LCD.