User Picture is a property on the User entity.
It's created via the standard profile.
If you used minimal or a custom profile, you may not have this in your site.
To get it back, copy these files from core/profiles/standard/config/install to your site's config directory and import config.
- core.entity_view_display.user.user.compact.yml
- field.field.user.user.user_picture.yml
- field.storage.user.user_picture.yml