Can I share my in-app purchases using the Apple Family Sharing Program or Family Sharing?

Yes. Please follow these instructions:
On your iPhone, iPad, or iPod touch
Go to Settings.
Tap your name.
Tap Family Sharing, then tap Set Up Your Family.
Follow the onscreen instructions to set up your family and invite your family members.
Ref : https://support.apple.com/en-am/HT201088