fb public pic

when the call returns, you have the fb id of user. you can link profile picture like this:

https://graph.facebook.com/” + facebookId + “/picture?type=square For instance: https://graph.facebook.com/67563683055/picture?type=square

There are also more sizes besides “square”. See the docs https://developers.facebook.com/docs/graph-api/reference/v2.2/user/picture.

Also, I think (not tested), you can also request profile_pic variable provided you have granted access to this field in the app from user.

What I mean when fb user data saved in wordpress, can I also save the public_pic,

yes, you can save the pic as user_meta.

call this endpoint update_user_meta:

https://localhost/api/user/update_user_meta/?cookie=COOKIE-HERE&meta_key=profile_pic&meta_value=facebookId

you can then use this fb id in your script as:
https://graph.facebook.com/” + facebookId + “/picture?type=square
or value can be profile pic path.