I’ve figured this one out so will answer my own question just in case it is of help to anyone else. I added the following to the custom css to set the font size within the “Events” element:
/*
* change events meta font sizes
*/
.fusion-events-meta h2 { font-size: 14px; line-height: 1.2 !important; }
.fusion-events-meta h4 { font-size: 12px !important; }