How to save in Cookies value?

Question

Node.js

I create a session like this:

import session from 'express-session';
import cookieParser from 'cookie-parser';
import MongoStore from 'connect-mongodb';

app.use(cookieParser());
app.use(session({
    secret:'yes is not bad',
    name : 'sessionId',
    resave: false,
    saveUninitialized: true,
    store: new MongoStore({
        url: connectionOptions
    })
}))

Cookies like this:

router.get('/',(req,res)=>{
    if(!req.cookies.cookieBad){
        let items=[];
        res.cookie('cookieBad', items, {
            expires: new Date(Date.now() + 999999),
            httpOnly: true
        });
 }
});

I add data like this:

router.post('/set',(req,res)=>{
            let items=req.cookies.cookieBad;
            items.push(req.body);
             res.cookie('cookieBad', items, {
                expires: new Date(Date.now() + 999999),
                httpOnly: true
            });
});

After reloading the browser, the values ​​in the cookies are reset to zero ...
How to store the values ​​​​in the cookies permanently so that they are updated only after adding a new value and am I doing the right thing with adding and creating them?