Can I transfer photos from my iPhone to only be on my iPad?

If when you acquire your iPad you initially leave iCloud Photos enabled for both iPad and iCloud, all photos on your iPhone will be automatically synchronised via iCloud with your iPad. All photos are now in three locations - iPhone, iCloud and iPad.

Now you can decide how you wish to continue synchronising your devices with iCloud - recognising that if you disable iCloud Photos on either device, photos will no longer synchronise between iPad and iPhone. Deleting any photo from iCloud Photos will also delete the corresponding photo from whichever device still synchronises with iCloud.

Disabling iCloud Photos on both devices completely severs the link with iCloud; Photos deleted anywhere will only be deleted from where the deletion is made.

Have you considered using a third-party cloud service, such as Google, to save/synchronise photos? Google provides 15GB of storage free of charge.

If your existing iCloud storage is limited (you only have 5GB for free), you can subscribe to an iCloud+ plan:

Upgrade to iCloud+ - Apple Support

iCloud+ plans and pricing - Apple Support

Having disabled iCloud Photos, if your objective is to continue using your iPhone camera - but for long term storage keep photos that you have taken with your iPhone on your iPad - you will need to manually move photos from your iPhone to your iPad. You might consider periodically using AirDrop to copy photos to your iPad, or semi-automate the process using a third-party File Manager App.

How to use AirDrop on your iPhone or iPad - Apple Support

Yes, possible, but you'll need to decide how you are intending to use your photo storage.

Consider that your iPhone (and iPad) camera saves photos that you take to your Photo Library. Your Photo Library can either be saved locally on just the device - or can be synchronised with your iCloud Photo Library. If you disable iCloud Photo Library in iCloud settings, photos will not be synchronised with iCloud - or with your iPad.

Settings > [Your Name / AppleID] > iCloud > Photos > Sync this iPhone | iPad - set to OFF

You might choose to allow your iPhone to synchronise its photos with iCloud - but choose to disable this feature for iPad. This would allow your Photos to be automatically synchronised with iCloud, but not with your iPad. The same is true in reverse.

Similarly, you might disable synchronisation with iCloud for both iPad and iPhone.

If you disable iCloud Photos, your photos will now be included in your iCloud backup - and will continue to occupy space in your iCloud storage. Should you choose to do so, you can deselect Photos from your backup settings - but this runs the risk of losing cherished photos if something were to go wrong with a device.