Is there a way to lock contacts on an Iphone so my child can not change or add to them?

NO. "Don't allow changes" does not prevent editing contacts. It prevents allowing other apps to access contacts.

Yes in Restrictions. Go to Settings > General > Restrictions (enter your password for Restrictions or set it on), then on Privacy > check Don't Allow Changes.

elcpu wrote:

Yes in Restrictions. Go to Settings > General > Restrictions (enter your password for Restrictions or set it on), then on Privacy > check Don't Allow Changes.

No, that is not what it does.

I just tested this and even with restrictions on I was still able to add and delete contacts that were already in my contacts app. It just made it so I couldn't change anything with my email accounts or add contacts to my email account but I could still delete all my contacts in the contact app.I don't think that there is a way to do what you're looking for. – AJ

elcpu I just tested your suggestion and couldn't get it to work. I was still able to delete contacts in my contacts app as well as add them. Were you able to get it to work, if so how?-AJ

No. There is no way to do that other than don't let your child play with your phone.

If you want them to be able to play a game or something specific, then use Guided Access.