How to calculate no of day's present in month based on given date

I have the requirement of finding a total number of days in a month based on date. For e.g I have a date with me i.e. 15 April 2021 then a number of days must return 30 as April month consists of 30 days. If I have a date of 02 Feb 2020 then the number of days should return as 29 as it is a leap year.