Use the below classes to change the size of the avatars
.avatar-xxs
.avatar-xs
.avatar-sm
.avatar-md
.avatar-lg
.avatar-xl
add .rounded-circle class to make an avatar image circle
.avatar-md .rounded-circle
.avatar-lg .rounded-circle
.avatar-xl .rounded-circle
Use the below classes to change the shapes of the avatars
.rounded
.rounded-circle
.img-thumbnail
.rounded-circle .img-thumbnail
Create and group avatars of different sizes and shapes with the css classes. Using Bootstrap's naming convention, you can control size of avatar including standard avatar, or scale it up to different sizes.