Can I see my family’s iCloud storage from our shared account

No. You'll need to ask them individually to clean up larger items if they can. From Share iCloud+ with your family - Apple Support:

See how much storage your family's using

Use the steps below to see how much storage your family is using and upgrade if you need more. 

If your family is low on iCloud storage, all members get a notification. Then the family organizer or family member that purchased the plan can buy more—up to 2TB—at any time.

etc.

tt2