https://www.techradar.com/news/best-portrait-lens

Everybody wants to look good on paper, especially when the paper in question happens to be a photo print. So what kind of lens makes people look their best? With a full-frame Canon or Nikon DSLR, an 85mm prime lens is ideal. If you’re shooting with an APS-C format camera like a Canon EOS 7D Mark II or Nikon D500, a 50mm prime that gives roughly the same ‘effective’ focal length is the best portrait lens for the job. 

These lenses enable you maintain a natural distance from your subject for head and shoulders or half-length portraits, neither crowding in and making people feel awkward, nor being too remote to give direction.