Iphone unavailabe

Dear Apple support.

I used iphone 6s plus before. However, after I switched to iphone xs and iphone 11 pro max, after a long time I did not open and use iphone 6s plus so I forgot the password to log in to the device. My iphone 6s plus is currently unavailable. I still have a lot of personal and family photos saved on the device. I have tried every way to access it using the old icloud but it did not work. I really hope apple can help me to retrieve the photo data in my iphone 6s plus

[Edited by Moderator]