It avoids pixelation and awkward image stretching and keeps your images looking professional.
Science! There is study published by the Psychological Science that summarizes
a. Smile with teeth
b. Dark-colored suits, light colored button downs
c. Jawline with a shadow
d. Head-and-shoulders, or head-to-waist photo
e. Squinch
f. Asymmetrical composition
g. Unobstructed eyes
You want to share some of your hobbies or activities? Great! Use a closeup image where people can recognize you in the profile picture and your passion, hobbies, landscape travel images in the cover or feed post, stories, reels, etc.