Alternate SMS application for iPhone

Hello everybody! I am a longtime Android user, and I just got my first iPhone (8 Plus). I wanted a change of pace, and to see how the other half lives, so to speak! Anyhow, I am trying to find a SMS application like what I used to use on my Android phone, that does not need a network connection to work. I have tried about six so far from the App Store, but they all require the other person to have the same app on their phone, and they all required internet. On my Android, I was able to text everybody with no network connection, and regardless of what type of phone they were using. The Apple Message app is OK, but is it kind of plain and dull, and I would like another option. From what can see so far, there is none. I saw a few apps that used a mesh network, but that will not help me. It is not the end of the world if I have to keep using Message, but though I would ask other Apple users for more ideas! Thank you!