Below are the steps to reopen closed tabs on Safari browser:-
1. Launch the Safari browser on your iPhone.
2. Hit the tab icon on the lower left corner of your screen.
3. Press and hold the (+) icon for a few seconds.
4. Scroll through the options on the list to locate the tab you want to reopen, and then tap on it.
Read More:-
https://techzeel.net/how-to-close-all-tabs-on-iphone/