My iPhone memory is full with photos or videos.

if You are using iCloud photo library it is an mirroring service so yes what you delete on one device it delete on iCloud server so on other device too

shahid246 wrote:

How do I transfer photos and videos from iPhone storage to iCloud?

You turn on iCloud Photos in the settings which should allow your photos to upload to iCloid.

i cloud is turned on so does it mean they are in both places?

Yes, it does.

if I delete phitoscand videos from my phone, will they delete from ICloud?

Anywhere that you delete iCloud photos, will delete them on all of your devices that are using iCloud photos.

i have two phones that use the same Apple ID, if I delete photos on one phone, will they delete from both phones? And from iCloud?

Yes. As explained, iCloud Photos is a syncing service so whatever you do on a device using the same Apple ID/iCloud account on another device using the same credentials, will take place ... deleting, editing etc.

Also if You don't have free minimally 15% of the internal storage The system will bo not able to provide the synchronisation process

Save manually to pc the photos and videos