Duplicating 2 iPhones

Good day to all,

I am using two iPhones, (6+ & X), and an iPad Pro, both phones are fitted with sim cards from different countries and I would like to make it in a way where I do not have to switch phones to find the relevant data i need.

For example I am using my iPhone on safari and the battery runs out or I put it down in the kitchen, I pick up my other iPhone in the room and still able to continue off where i was left off. I would also like to be able to do that to my iPad too.

If you would be so kind to show me the steps to get there, it would greatly help.

Thanks