From your description, I take it you are using iCloud Photo Library:
Get help with your iCloud Photo Library - Apple Support
See the section:
You can turn off iCloud Photo Library on a single device when you follow these steps:
- On your iPhone, iPad, or iPod touch, go to Settings > iCloud > Photos and turn off iCloud Photo Library.
- On your Mac, go to System Preferences > iCloud > Options next to Photos, then deselect iCloud Photo Library.
- On your Apple TV (4th generation), go to Settings > Accounts > iCloud and under Photos press Select to turn off iCloud Photo Library.
If you have Optimize Storage turned on, you might not have all of your original photos and videos on your device. To download the original photos and videos on your iOS device, go to Settings > iCloud > Photos and select Download and Keep Originals. On your Mac, open Photos, choose Photos > Preferences, then select Download Originals to this Mac. Then you can turn iCloud Photo Library off. You can also select the photos and videos that you want to download from iCloud.com.
Then you can transfer the photos to your PC using:
Import photos and videos from your iPhone, iPad, or iPod touch - Apple Support