Have you bought 2nd hand?
Each Apple device is linked/associated with an Apple ID of the person who did the setup.
Activation Lock prevents anyone who is not the owner from using this iPhone.
To unlock the Phone, you need the Apple ID and password of the previous owner, that were used during set up.
So try to contact the previous owner.
Apple cannot help you.
The previous owner have to read -> this Apple article: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
See also the following Apple articles:
Activation Lock for iPhone, iPad, and iPod touch
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
How to remove Activation Lock
How to remove Activation Lock – Apple Support (UK)