I needed some of my gmail contacts to email them and get some info, so I decided to sync my google accounts to my iPhone. The problem is that I have some repeated contacts and I want to delete those from the iPhone, but I don’t know if that will just delete them on the phone or if it’ll affect my google contacts too.
If you're only seeing the duplicates on your iPhone, they're most likely in different Groups. You can check this by opening Contacts on your phone and tapping the Groups button (screenshot below). If you see a group called iPhone, those are stored exclusively on your phone and deleting them will not affect your Google contacts. You can uncheck the Google group to show (and ensure you only delete) contacts from your phone. Deleting contacts from the Google group will affect your Google contacts.