If you use the native Messages app to send iMessages or SMS messages from your iPhone, then you may have noticed the avatar that generally appears in the navigation bar. When you have a contact picture configured for the recipient, that picture displays here; otherwise, you’d see the recipient’s first and last initials instead.
Apple stopped supporting this feature on smaller handsets like the iPhone 5s and earlier with some of the latest iterations of iOS, limiting it to larger-displayed devices such as the iPhone 6 and later. On the other hand, a new free jailbreak tweak dubbed Navatar by iOS developer EthanRDoesMC changes that.