iPad photos and iPhone

Yes. I suggest that you read all of the following notes before proceeding.

You can disable Photos in iCloud on your iPad, but be aware that iCloud is a synchronisation service - and photographs that have been synchronised to your iPhone, originating from your iPad, may not be subsequently accessible on your iPhone.

Also be aware that having disabled Photos in iCloud on your iPad - and deleted photos from iPad - should you subsequently re-enable this service, some photos may be removed from your iPhone.

Leaving Photos in iCloud enabled on iPhone allows you to keep an accessible copy of your photos in iCloud - allowing other devices signed-in to your AppleID (such as other Apple devices or your PC or Mac) to access your photos. If you also disable this service on your iPhone, your Photos will be included in your iCloud or iTunes backup - and can be restored to your iPhone should data recovery ever become necessary.

If you decide that keeping photos accessible to other devices is not required, the best way forward is to first disable Photos in iCloud on your iPhone; if prompted, keep a copy of all existing photos on your iPhone. Next, when you are certain that your Photos are safely copied to iPhone, you can disable Photos in iCloud on your iPad - after which you can delete unwanted photos from iPad.

With this in mind, you can disable Photos in iCloud individually for iPhone and iPad here:

Settings > [Your Name] > iCloud > Photos > iCloud Photos - set to OFF

This support page might provide some additional helpful information and insight:

Keep your photos safely stored and up to date on all of your devices - Apple Support