Find Windows Lock Screen Images
This PC - C: - Users - [Your User Name] - AppData - Local - Packages - Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy - LocalState - Assets
The path above is where lock screen images are stored
Turn on the option to view hidden files and folders
Go to This PC - C: - Users - [Your User Name] - AppData - Local - Packages - Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy - LocalState - Assets
Sort the images by date
copy some big ones
paste the big files where you want them
rename the pictures with a .jpeg extension