These directions work for iOS 12 and up, including iPadOS.

Tap and hold theTabbutton, which looks like two stacked squares.

TapClose All [#] Tabs.

The iPhone with the tabs menu open

Tap the same button once more to confirm.

This will close all tabs immediately.

The Tab menu is also how youlaunch a private browsing session.

The Clear History and Website Data button in Safari’s settings on iPad

initiate the configs appand tapSafari.

Scroll down and chooseClear History and Website Data>Clear.

To close all tabs at the same time, chooseClose Tabs.

The Close Tabs button in Safari’s settings for iPad