I'm reasonably familiar with train travel in Italy, but I am unfamiliar with MZP and Lecco.
I will arrive at MXP on a Sunday morning next month. I believe I need to take the Malpensa Express, after tapping in, to Milan Centrale, then board a Trenord train direction Tirano.
Sounds simple enough, does traveling on a Sunday create any issues?
If you are used to train travel, Just put "Malpensa Aeroporto" and "Lecco" either on trenitalia.com/en.html or trenord.it
Both sites sell through tickets from the airport to Lecco and both have an English version, but Trenord runs the local trains and substitute buses around Milan. Pick your day and time of travel from the list and click search. You'll learn in 2 minutes about the level of service on Sundays. I doubt the all journey will take less than 3 hours.
Trenitalia's site shows if/where to transfer under the "Changes" link, Trenord must have a similar option.
After you have arrived in MXP, get your phone, open the same site you used to check the schedules and buy a through ticket from Your Terminal to Lecco. MXP has 2 Terminals and 2 stations,