Screenshot from the macOS screen allowing one to setup and allow "age appropriate experiences in apps". The text goes on to explain how Apple approaches this: Age-Appropriate Experiences in Apps Share that you're an adult so you're not limited to child and teen content in apps.
By default, you'll always be asked if you want to share your age range. You can change this in Age Range for Apps settings. Age and Birthday Stay Private. Apps will only know that you're at least 18 years old. Syncs Across Devices - Sharing syncs to any iPhone, iPad or Mac signed in with your account.