Recovering iMessages from old iPhone?

So I have an old iPhone 7 Plus and I have some sentimental messages that for some reason never backed up to iCloud and didn't transfer over to the new phone. The phone has of course been deactivated, but is there a way to still get these messages? They are still on the phone. Thanks for any help. These messages are from my girlfriends deceased father and it would mean the world to her to be able to have them.