Should I change the font size if my recipients complain it’s too big or small?
No, using Missive’s default font size when writing emails is the best option because you are telling Missive to not force any font size on your emails. This means that whatever font size your recipients see on their end is according to their preference. If they say it’s too big or small, they most likely have a Zoom or Font size setting they can adjust in their email app.