Interested to know actually because I want to avoid the crowds of that day.
Here's the Pope's schedule for 2019:
http://www.papalaudience.org/schedule
https://thecatholictraveler.com/papal-calendar/
Unless otherwise noted, all celebrations are at St. Peter's Square or the basilica.
Sundays and Wednesday are the usual days. The Vatican Museums are closed on Sundays except for a few "free" hours on last Sundays of the month; NOT a good day to try and do those.