Clear the history and cookies from Safari on your iPhone, iPad
https://support.apple.com/en-us/HT201265
Learn how to delete your history, cookies, and cache in Settings.
Delete history, cache, and cookies
To clear your history and cookies, go to Settings > Safari, and tap Clear History and Website Data. Clearing your history, cookies, and browsing data from Safari won't change your AutoFill information.
iPhone Safari Settings showing Clear history and website data.
To clear your cookies and keep your history, go to Settings > Safari > Advanced > Website Data, then tap Remove All Website Data.
To visit sites without leaving a history, turn Private Browsing on.
When there's no history or website data to clear, the setting turns gray. The setting might also be gray if you have web content restrictions set up under Content & Privacy Restrictions in Screen Time.
Block cookies
A cookie is a piece of data that a site puts on your device, so that site can remember you when you visit again. To choose whether Safari blocks cookies, tap Settings > Safari, then turn on Block All Cookies.
iPhone Safari Settings with Block All Cookies enabled
If you block cookies, some web pages might not work. Here are some examples:
You will likely not be able to sign in to a site even when using your correct username and password.
You might see a message that cookies are required or that your browser's cookies are off.
Some features on a site might not work.
Use content blockers
Content blockers are third-party apps and extensions that let Safari block cookies, images, resources, pop-ups, and other content.
To get a content blocker:
Download a content blocking app from the App Store.
Tap Settings > Safari > Extensions.
Tap to turn on a listed content blocker.
You can use more than one content blocker. If you need help, contact the app developer.