can I share an icloud photo library with my family

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. 

You can also share photos without Family Sharing. See: How to share albums in Photos on your iPhone, iPad, and Mac - Apple Support

Note that there is no way to share all of iCloud Photos, even with Family Sharing and even if sharing an upgraded iCloud Storage plan. See the following from Share an iCloud storage plan with your family - Apple Support

When you share a storage plan, your photos and documents stay private and everyone keeps using their own accounts with iCloud—just like when you have your own storage plan. You simply share the space available in the iCloud storage plan with your family members, so you only have one plan to manage.