ChatGPT 4o mini was handling the search. You can't currently set ChatGPT Search as your default search engine on mobile. You can use ChatGPT Search inside the mobile app if you need to.

Set ChatGPT as the default search engine in Chrome and Edge ChatGPT has a search extension that you can install on Chrome and Edge or other similar Chromium-based browsers.

But you can also set ChatGPT as the default search engine in your browser, so you receive ChatGPT's response to your query instead of Google search results.