You have forgotten the Apple ID password say example1@icloud.com that is signed in the old iPhone .
Reset Apple ID password using find my iPhone .
On your iPhone device , click on home scroll to the next page > click on extras > you will find find my iPhone click on it , enter your Apple ID only , click on forgot Apple ID or password , click on next.
Reset options - choose how would you like to reset your password ( a )
Click on reset through mail and click on ok .
Then open your rescue mail with web browser ( server account ) , open mail > click on reset password > two fields will be shown .
( a ) new password …..
( b ) verify password ….
Enter the credentials , and click on reset password , the password is changed .
If you click on - answer security questions - click on the right arrow .
Date of birth , verify your date of birth to continue > fill up the credentials > click on next and same pop up window will appear .
New password ….
Verify password ….
Fill up the credentials and click on reset password , the password is changed .
( a ) If you lose answers for Apple ID provide credit card details that was added in the account .
( b ) if you have lost Apple ID password provide invoice copy of Mac to apple support advisors .
( c ) Contact apple support , they will send a link on mail account , click on link after 24 hours to reset apple id password , however the link is valid for additional 3 hours .
( d ) Support pin is used by apple support advisors to verify the account when you know apple id password Generate a temporary Support PIN - Apple Support
Note : don't reveal any Apple ID and credentials and post here .
See the article If you forgot your Apple ID password - Apple Support
The photos can be accessed from old iPhone View photos in the Photos app on iPhone - Apple Support when photo library was set up Set up and use iCloud Photos - Apple Support
