Unfortunately, that’s never been a thing on iPhone. Safari has never had a configurable start page to a particular website. It’s never had a Google search bar in the middle of the start page either.
The start page on iPhone has always been collection of favorites and recent websites visited.

You can however, always use the address bar to perform a Google search. The only other way to get to a Google search automatically when opening Safari is to make a home screen shortcut or bookmark to the Google home page.
To do this, you open the Google search home page, tap on the share icon and select add to home screen.
click here ➜ Bookmark a website in Safari on iPhone - Apple Support

This will create a shortcut icon on the iPhone’s home screen to open Safari directly to Google.com.