Q: create new apple id get contacts from old apple id

you can go ahead and create a new Apple ID for yourself. Your contacts do not get affected on the phone 

If you are syncing contacts via iCloud, you will want to turn that function off (settings app > iCloud) before changing ID's on the phone. Once you turn it back on with the new ID, you should have to option to Merge them which will retain them.

If you are not syncing them with iCloud, doesn't matter. They will still be there when you change IDs.

Big mistake.

Simple solution... stop sharing Apple IDs.  Setup family sharing.  Give them their own IDs.  Disable iPHone cellular calls in the FaceTime settings on all their phones.  Use their own Apple IDs for their devices.

By making yourself a new ID, you're creating a headache with all your past iTunes / AppStore purchases as each one is tied to your ID.  You'll have to redownload and re-pay for everything again.

Actually Templeton has a point. You would be better served creating the new IDs for them and keeping the existing one for yourself. And potentially using Family Sharing: Family Sharing - Apple Support