How do I know if my iCloud is on or setup?

Set up iCloud on your iPhone, iPad or iPod touch

1. On your iPhone, iPad or iPod touch, go to Settings > [your name].
2. If you do not see [your name], tap “Sign in to your [device]”, then enter your Apple ID and password.
3. Do one of the following:

• iOS 16, iPadOS 16, or later: Tap iCloud, then turn on each app or feature you want to use. Tap Show All to see more apps.
  • 
  • iOS 15, iPadOS 15 or earlier: Tap iCloud, then turn on each app or feature you want to use.

If you are the owner or the owner has shared all information with you then to open Activation Lock:- If it is Activation locked, read here --> Turn off Activation Lock - Apple Support Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Learn how to remove a device from a previous owner's account.

If you are not the owner and do not have the Apple ID and Password then there is no way that you can get into this iPhone unless the original owner shares the Apple ID and password with you. If you are lucky you can get into this iPhone if they (owner) accidentally remove the device from their Apple ID.