Calculating dates


How can I create a code to return different dates based on a data entry? What I want is for a site visitor to input a date, and the result should return three dates with the name of day; Date 1: +2days, Date2: +5days, Day3: +8 days; the entry date is day 0.

For example: If the user enters 11/05/2021, the returned result should be:
Date 1: Tuesday 12/05/2021;
Date2: Sunday 16/05/2021; and
Date3: Wednesday 19/05/2021.

Many thanks in advance.