I have not used my Iphone 8 and have forgotten my password

If you forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage  -     

Apple ID – Forgot Password  *      

See instructions in If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support