Upload avatar for post comment

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:

1. 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.
2. 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.
3. 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.