You’re approaching this from the wrong angle.
The way to do it is to use Button widgets, set to Push mode and each connected to a different virtual pin.
The button will send a “1” when pressed and a “0” when released by default, and there’s no need to change this default behaviour.
The code running on the MCU will include a BLYNK_WRITE(Vpin) callback for each button widget. You will only want to take action when the button is pressed (not released) so you’ll start by only proceeding if the received value is a “1”.
At that point you can take whatever action you want, such as calling a function with a parameter which sends the specified IR code.
There are quite a few projects around where this has already been done. Here is one:
I’ve not studied the code in this example, and as it was written by a newcomer it may well have some serious flaws, but doing more searches will probably deliver something you can work with.
Pete.