On a Mac, open the Photos app
Sign in with your Apple ID if needed
Go to Photos > Settings > iCloud
Turn on iCloud Photos
Select Download Originals to this Mac
Keep the Mac connected to Wi-Fi and power until all photos finish downloading
To export them, select all photos in Photos
Choose File > Export > Export Unmodified Original for all items
Save the exported files to a folder on your Mac
On Windows, install iCloud for Windows
Sign in with your Apple ID
Turn on Photos
Click Download Photos
Select All
Download the photos to your PC
On iPhone or iPad, open the Photos app
Make sure iCloud Photos is enabled in Settings > Photos
Keep the device on Wi-Fi and power to download full-resolution originals
Use AirDrop, Files, or a computer transfer to copy the photos off the device
On iCloud.com, sign in with your Apple ID
Open Photos
Select photos manually or in batches
Click the Download button
Repeat until all photos are downloaded
For a full copy of your data, go to privacy.apple.com
Sign in with your Apple ID
Request a copy of your data
Select iCloud Photos
Submit the request and download the archive when it is ready