How can I see a family member’s pictures in the family cloud?

See the following from Share iCloud+ with your family - Apple Support

When you share an iCloud+ subscription, everyone in the family group uses their own account. That way your photos, documents, and other information stay private, even though you're sharing access to the service. You simply share the features and space available in iCloud+ with your family members, so you only have one plan to manage.

You and your family can share selected photos. See the following from Family Sharing - Apple

When you set up your family, a shared album is created automatically in the Photos app on all family members’ devices. Everyone can add photos, videos, and comments to the album whenever they like and get notified when something new is added. 

One caution about shared Albums. They are a simple and easy way to show off your photos to others, but are only meant for viewing photos. Thee copy of your photo in the shared album will be downsized to 2048 pixels at the longest edge, and many metadata may have been stripped to protect you from giving away more personal information than you intended. See the footnotes in this document: How to share albums in Photos on your iPhone, iPad and Mac – Apple Support (UK)

If you want to give your family members access to high quality versions of your photos, share the photos you want to share in a folder on iCloud. https://appleinsider.com/articles/18/11/04/how-to-share-icloud-photo-library-photos-with-anyone-and-revoke-permission