Contact Sync

Guys how do I stop my contacts from syncing between my 2 phones? I a Samsung Galaxy S8 and an S9. Ever since I switched to Verizon my phones sync contacts, usually after an update. One phone is personal and the other is work. It's bugging me that I delete or add a number on one and it shows up or disappears on the other. Or, a number that has been deleted on both phones magically reappears. When adding a new contact I am saving it to the phone. I am not adding it to my Samsung account, Google account or the Verizon cloud. I have over 400 contacts on each phone and am scared to delete anything from either phone because I am worried that they will sync and I'm going to lose a number I need. I have set "Save to phone" as the default on both phones but the sync is still happening. I need these two phones to be completely separate. I have never set up the Verizon cloud thing. If it has anything to do with Google drive am going to have a difficult time. It was previously what we used for work but not anymore. Now when I go to Drive my work email shows in the box but I am unable to change. When you tap the box for the email the keyboard doesn't come up and the only option is "copy or select all". What am I missing?