I’m not sure what it is that you’re looking for.
1) If you upload new JSON files to a site then the JSON files will override the groups stored in the database.
2) There is no reason to sync these field groups unless you plan to edit them on the site you uploaded them to
3) If you still want to auto syn field groups then you might want to look at this https://support.advancedcustomfields.com/forums/topic/automatic-synchronized-json/
