Setting up second iphone

You have to decide. You could set up a second Apple ID. That would keep the two worlds entirely separate. But then some do not want to keep them entirely separate. That in turn means it turns into a management task making sure what you have on each is what you want. You figure out the best balance for your purposes.

Should you want to create a new ID, This document explains how to create a new Apple ID (create an Apple Account) --> How to create a new Apple ID - Apple Support

Incidentally, you can share items between IDs, but you have to set up Family Sharing with yourself. To learn how to set up Family Sharing, read this support article --> Set up Family Sharing - Apple Support

Read the support article titled: 'Set up your iPhone, iPad, or iPod touch'. Click here--> Set up your iPhone or iPad - Apple Support