Good evening Rachel and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
Is it possible to change the size of the tribe-event-date-end and tribe-event-date-start in the ecs-event-list when displayed with the short code?
The short answer is yes.
However, The Events Calendar Shortcode, is actually not our plugin, but rather a plugin made by a third-party.
I would recommend reading the following article to understand how to identify and update the CSS rules pertaining to that plugin’s appearance: https://theeventscalendar.com/knowledgebase/using-google-chrome-developer-tools/
As a side note, we also have a plugin that offers complete shortcode capabilities (including full views), when you get a copy of the Events Calendar Pro: https://theeventscalendar.com/product/wordpress-events-calendar-pro/
Have a good weekend,
Geoff B.