Adding extra information in user object in passport.js

I want to make some users be admins i heard i can do this if i add a class to a user but i don't know how here is my code. I want to have some information only be displayed to admins like edit buttons and delete buttons.

app.use(function(req, res, next){
res.locals.currentUser = req.user;
res.locals.error = req.flash("error");
res.locals.success = req.flash("success");

next();
});

//AUTH 
app.get("/register", function(req, res){
res.render("register");
});
app.post("/register", function(req, res){
var newUser = new User({username: req.body.username, password: 
req.body.password});
User.register(newUser, req.body.password, function(err, user){
    if(err){
        console.log(err);
       req.flash("error", "You Can't Register");
        return res.render("register");
    }
    passport.authenticate("local")(req, res, function(){
       req.flash("success", "You Have Successfully Registered!");
      online = online +1;
  console.log("users that are online: " + online);
       res.redirect("/blogs"); 
    });
});
});

app.get("/login", function(req, res){
res.render("login"); 
});
// handling login logic
app.post("/login", passport.authenticate("local", 
{

    successRedirect: "/blogs",
    failureRedirect: "/login"
}), function(req, res){

});

function loggedIn(req, res, next) {
if (req.user) {
   online = online +1;
console.log("users that are online: " + online);
}
}

via fanis theologiths