Safari uses Google as the default search engine out of the box, but it's not the only option. You can choose other search engines like Bing, Yahoo or DuckDuckGo if you prefer them.
Change the default search engine in Safari on iPhone and iPad
To get started, open the Settings app and press "Safari."
Next, under the heading Search, press "Search Engine."
Lastly, select the search engine you want to use by default when you are inside Safari. To select a search engine, press it. You can choose either Google, Yahoo, Bing or DuckDuckGo.
Unfortunately, these are the only options. Apple does not allow you to select other search engines by default. You can still navigate to the search engines in Safari and search them from their website, but that's it. The only way you get more options here is if Apple adds them to a future version of the iOS operating system.
However, there is a caution to consider here. This setting only changes the default search engine used when searching from Safari. If you use Siri or Spotlight to search, they still use Google. It's not ideal, but Google pays a lot of money to Apple every year to make it the situation we need to live with. Unfortunately.