The lens of 18- 105 has pincushion distortion at the medium and long focal length (35- 105 mm). If the face is not in the center of the picture when taking pictures, it will be deformed and look fat. However, there is barrel distortion at the lens 18mm end, which may make people look fatter when taking pictures. Only when it is about 24 mm, the deformation is very small. You can try this focal length.
If you often take portraits, it is of course necessary to have a fixed Jiao Da aperture lens. It is recommended to use 50mm 1.8G, which is cheap and has high imaging quality, and a large aperture will have a good blur effect.
In addition, you should also pay attention to the angle when taking pictures. The horizontal shot has little deformation. Shooting people from bottom to top will make their legs longer and their heads smaller. Shooting people from top to bottom will highlight their faces.