Your friend needs to follow the steps in this Apple Support Link: What to do before you sell or give away your iPhone, iPad, or iPod touch - Apple Support
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You will need a SIM to activate that phone.
As Michael said above if you run into an Activation Lock screen you will not be able to activate it.
And I will be mad as **** I played the person I got it from 800 dollars
In your initial post you said you got this from a friend. If your friend doesn’t know the AppleID to remove activation lock, presumably they’d at least refund your money?
It does beg the question why anyone would pay $800 for an iPhone 6. The going used rate from online sellers is about $200-$250 (e.g. gazelle.com).
Question: just got a disabled iPhone 6 how do I undisable if I never synced it to my computer