MS Flows | How to add days function works

Question: How to use add days function in MS flows

OR

Question: How to play with Date and time in MS Flows


Answer:

This answer shows you to add 7 days in SharePoint Date field


formatDateTime(addDays(formatDateTime(string(['License_x0020_Expiry_x0020_Date'])), 7))

1) Convert that date field to string
2) Convert into ISO 8601 format
3) Add 7 days
4) Return the ISO 8610 format date