How to send express-session to client not in same url? - node.js

Question

Can I please get some help, I have been searching all over the internet for this and I cannot seem to find the answer that I am looking for.
So I would love to implement expression-session and mongoDB as the store, so session creation I managed to get that done and also saving the session within the store i.e MongoDB managed to get that done.
The problem now comes to when I have to send the session cookie to the client, so I have my server(NodeJS) running on port 5000 and I have the client(ReactJS) running on port 3000, so now how can I send that cookie to the client and flag it as httpOnly cookie?
This is how I tried to setup express-session
mongoose
.connect(MongoURI, {
useNewUrlParser: true,
useCreateIndex: true
})
.then(() => console.log("MongoDB connected..."))
.catch((err) => console.log(err));
const mongoDBstore = new MongoDBStore({
uri: MongoURI,
collection: "mySessions"
});
app.use(express.urlencoded({ extended: false }));
app.use(express.json());
app.use(
session({
name: COOKIE_NAME,
secret: 'SESS_SECRET',
resave: true,
saveUninitialized: false,
store: mongoDBstore,
cookie: {
maxAge: 1000 * 60 * 60 * 3,
sameSite: false,
secure: false
}
})
);
This is where I wanted to send the cookie once user logs in
router.post("/login", (req, res) => {
const { email, password } = req.body;
if (!email || !password) {
return res.status(400).json({ msg: "Please enter all fields" });
}
User.findOne({ email }).then((user) => {
if (!user) return res.status(400).json({ msg: "User does not exist" });
bcrypt.compare(password, user.password).then((isMatch) => {
if (!isMatch) return res.status(400).json({ msg: "Invalid credentials" });
const sessUser = { id: user.id, name: user.name, email: user.email };
req.session.user = sessUser;
res.json({ msg: " Logged In Successfully", sessUser });
});
});
});