Transferring from iPhone 6 to iPhone 8

I am unsure of the sequence of actions with respect to making the change. I will back up the iPhone 6 on iCloud. I understand I next have to do a reset on the iPhone 6 but do I do this before or after I remove the sim which I expect to place into the iPhone 8. Once I place the sim into the iPhone 8, I should start the restore from iCloud process but the apple support says to use the apps and data screen. I can’t find where this screen is on the iPhone. How do I initiate the restore?