If you’re using iCloud Photo Library. The only thing you can do is go Settings —> Photos —> Optimise Phone Storage. This will then only keep the last 1000 photos on your device and thumbnails for the rest. It will then download pics as and when required if you try to view one that’s not already on the phone.
If you’re not using iCloud but using Photos on a Mac then you used to be able to select albums etc in iTunes. I haven’t looked in a few years though so not sure if you still can.
There is option on icloud that transfer or download your photo to computer when you connect iphone to computer. For that you need to download desktop version of icloud on computer.
or try this
go to setting – icloud – photo – then turn on icloud photo library. Now when you take new photo, picture or video on your iphone, ipad or ios devices. It will upload automatically to icloud when you connect to internet on your device.