The free version of ChatGPT uses the older and less powerful GPT-3.5. A subscription to OpenAI’s ChatGPT-4 is $20 per month.
Microsoft just released it’s Copilot app for the iPhone and iPad which uses GPT-4, the latest version of ChatGPT. This enables users to use GPT-4 for free.
To start using, just download the latest version of Microsoft Copilot from the Apple App Store.
https://apps.apple.com/us/app/microsoft-copilot/id6472538445