Hey Gail,
Pretty much anything you can imagine is possible, but it comes down to the skills of the developer themselves in regards to whether or not they can actually realize the hoped-for possibilities.
By far the most important article you/your developer should read is our Themer’s Guide → https://theeventscalendar.com/knowledgebase/themers-guide/
That describes in great detail how to make custom calendar views in a safe way, so that you can continue to upgrade the actual plugin code underneath without breaking things. Very, very important!
Beyond that, I can’t think of many specific resources on our site since the rest of the customizing relates to general CSS, PHP, and WordPress knowledge, and the only resources we have on our site are specific to our plugins (i.e., not those “general” things).
I hope this information helps!
Cheers,
George