I want a date-timepicker in JS for a reminder app, when selecting any value it will show “Remind in 1 day” (according to the value selected)

For example I have a button in HTML

<html>
<head>
<body>
<button id="date-time"></button>
</html>
</head>
</body>

when clicking the button a datetime picker will pop up and on selecting the value it will show “Remind in 3 days” as per the value picked.