How to send email for a particular scheduled date and time ? [Schedule Email Feature]

Question

I tried cron jobs for scheduling but it gets triggered for each and every day at that particular time.

Also workaround Gmail API for scheduling, but there isn't a feature in Gmail API My requirement is to send a scheduled email for the given time by the user.

Here I'm using Postgresql as DB and for backend Nest.js

Kindly help me to figure out this issue.