Solution 1: I know that you don't want to change the EmailTemplate Module but what you can do is create a custom module and reuse documents from the original module to create a solution where it is possible to change the HTML code in the EmailTemplate, so to make the solution from Ronald work. What you can do is described in the following forum answer: https://forum.mendix.com/link/questions/87559.
Solution 2: Another solution could be that where you retrieve the template and create the new email object, you could use a regex expression to find the P tags or TD tags, or whatever tags you're using and use the replaceAll function to add some extra element styles.
My prefered solution would be solution 1 so that you are always in control of the HTML code in the database and when you add a piece in the template you don't have to check the microflow if this line is converted correctly.
Hope that helps.
I do not get your point. When designing the e-mail template you can style the template to your linking and change the lettersize there. So why do you want to change it in a microflow? Or am I missing your point here?
Problem is that you can not edit the HTML text in the CKEditor, but you could try to add this to the HTML code:
<p style="line-height: 90%;">paragraph text</p>