User Table Design

So i want to design user tables and flows for my application. The application is essentially a variant of social media app.

So a user can come up and use the app without creating an account. At the same time user can create an account and have a profile.

Now there are multiple challenges to this :

1. How can I map a logged in User with anonymous user
2. Multiple anonymous user from different device can be same user. How can i map this info.

From the frontend side, I'm gonna create an anonymous id for each landing user, there's gonna be a GA ID that google analytics drops in and sometimes user comes from instagram so they gonna have an instagram id. Based on these information i need to map multiple anonymous user to single unique user.

Help me with the design for this database. If there is any blog related to this design please let me know. Thanks in advance.