How can I get parent tree list (follow general tree)

I have millions data in database.how can I get each parent tree member list. like that:

But here is one problem I'm getting: only 5 users list
    I want to all list which is I'm or my child adding
    members or every tree member adding new member.

<pre>private DbContext db=new DbContext();

public List<user> GetUserListByParentId(int id)
{
    var data = db.users.where(x => x.parentid == id).ToList();
    
}