I think I understand what you want so ima give a shot at helping:
- In studio, simply play the game.
- In Explorer, look for the Chat section
- Inside the Chat section, you should see these inside of it
- Add everything inside there to your clipboard.
- Stop the Play session and paste everything into the chat section.
- Locate ChatSettings by following this directory: https://gyazo.com/d5346733a5d6a5215c04ffecdfa35453
- Open Chat Settings.
- On line 27 and 28, you can change the values to either true or false. (Although for you, set ClassicChatEnabled to false)