Vulcan/packages/telescope-theme-base/lib/client/scss/specific/_avatars.scss

.avatar-xsmall {
  .avatar-initials{
    font-size: 12px;
    line-height: 20px;
  }
}
.avatar-small {
  height: 24px;
  width: 24px;
  .avatar-initials{
    font-size: 13px;
    line-height: 24px;
  }
}