Yes, and there are special types of accounts for under-13 family members.

https://support.google.com/families/answer/7103338?hl=en

Having a Family plan for YouTube Premium (or other Google services) doesn't suddenly make it okay to use regular Google Accounts for young children. There are laws that apply here, and Google has special accounts designed to comply with those laws.

You can't just spin up a regular 13+ G Suite account for those family members, though.