Add days to Date object and then converting to local string?
Solution 1:
Without using any libraries, Vanilla JS solution:
const now = new Date()
const inFiveDays = new Date(new Date(now).setDate(now.getDate() + 5))
console.log('now', now.toLocaleString())
console.log('inFiveDays', inFiveDays.toLocaleString())
This even works when your date overflows the current month.