WordPress doesn’t have built-in profile pictures (Avatars) by default. See Settings > Discussion in the menu for available options.
So you may have a few options:
- Use Gravatar, as this is bundled in WordPress by default and free but
would not require a profile image upload button as its managed separately. - Look for an Avatar plugin that allows for programatically creating an upload
button in your Comments template, or one that pre-packs that functionality. There are several Avatar plugins around but I can’t be sure that they have the Comment form functionality you are looking for. - Use ACF to extend the user profile with an image, and then ACF form
to allow uploads via the Comments template.
For what its worth – I think allowing members of the public to upload their own images to your website like that is a generally bad idea. I suspect WordPress agree, which is why they include Gravatar.