On a recent visit my son set up my Canon MG3100 printer so that I could print documents from my mini iPad.
It works ok except that the size of the printing is too large, and I can see no way of reducing the size.
I would be grateful if anyone could let me know how to do this
I know nothing of either piece of kit but were I in your shoes I'd try two things.
Check the printer settings to see if there is a default font it uses when something sends it text and doesn't define a font. If there is, change it to something suitable.
Check the print settings on whatever it is on the iPad that you are using to create/send text to the printer. It may be set to a large font that you can change.