Hi, welcome to Apple Support Communities! My name is Jeremy, and I'm more than happy to help answer your question.
It is possible to add multiple accounts to your Apple TV. To do this, each family member must have their own individual Apple ID. "When each member in a household has an Apple ID, you can create unique user profiles on Apple TV associated with the Apple ID of each household member, with Up Next lists, system language preferences, paired AirPods settings, music, Game Center data, and content recommendations personalized for the currently active user." Do note that "iCloud Photos and One Home Screen are only available for the Apple ID associated with the default user on Apple TV. To change the default user, see Change the default user account."
In order to add new users, on your Apple TV, simply open Settings > Users & Groups then Add New User. You can also press and hold the TV button on your Siri remote to open the Control Center, then select Profiles > Add New User.
Hopefully this helps! For further answers, check out this article: Share Apple TV with multiple users - Apple Support.
Have a great day! 😁