Check iCloud Photos before changing the phone
Sign in to iCloud.com/photos with the Apple Account used on the old iPhone. If the library appears there, download a small test group first and confirm that dates, resolution, and videos are intact.
Do not erase, reset, or sign out of the old phone until you have opened the copied files on another device and made a second backup.
Import directly to a Mac
Connect the unlocked iPhone with a data-capable USB cable, open Photos on the Mac, choose the device in the sidebar, and import selected items or all new photos. Accept the accessory and trust prompts when they appear.
Wait for the import to finish before disconnecting the phone. Open several photos and videos from different years to verify the result rather than relying only on the item count.
Import to a Windows PC
Apple currently directs Windows users to install the Apple Devices app, connect and unlock the iPhone, trust the computer, and then import with Microsoft Photos.
If iCloud Photos is enabled and the phone stores optimized copies, the full-resolution originals may need to download before a cable import. Using iCloud for Windows or iCloud.com can be more direct in that case.
If the old iPhone is unavailable
Look for iCloud Photos first, then check whether an existing iCloud or computer backup is available. A device backup and an iCloud Photos library are different: photos already synced through iCloud Photos are not duplicated inside the daily iCloud device backup.
If the phone cannot unlock or power on and no synced library or usable backup exists, avoid repeated resets. Contact Apple Support or a reputable data-recovery specialist and ask about the risks before authorizing repair work.
Preserve originals before sorting
Keep one untouched copy with the original filenames and metadata. Create a separate working copy for renaming, cropping, restoration, or sharing.
After the files are safe, group family photos by person, branch, event, or approximate decade. Record uncertain names as notes instead of turning a guess into a permanent caption.