I found my iphone

If you are the owner of the iPhone 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 of the iPhone 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 to you. If you are lucky you can get into this iPhone if they (owner) accidentally remove the device from their apple ID.

See what lost mode does.

Lost Mode exactly does that. Please watch till the end.

Watch this GIF below