How can I get my new iPad to have same ID and password as my iPhone?

Use of the same AppleID and associated Password, as directed by Demo, will allow you to keep your iPhone and iPad synchronised via iCloud.

Your iPhone and iPad device Passcodes are, however, fully independent of each other. The only way to use and keep the device Passcodes to be the same is to set them manually:

Use a passcode with your iPhone, iPad, or iPod touch - Apple Support

Sign in with the same Apple ID and password that you use on the phone.

Sign in with your Apple ID - Apple Support