Dear sir my friend buy new 12 iPhone now he as been forget email ID and password.. what to do .. please help us

See if he can recover the ID/password. Use every email address he can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

For the Apple ID password, enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage            

Apple ID – Forgot Password