To answer your basic question. Yes.
You can make the map as big as you want.. using shortcode(s).
https://wp-events-plugin.com/documentation/shortcodes/
scroll down to Location Shortcodes
Or in the basic settings for the plugin for a generic site wide implementation.
Clustering of icons (map placeholders).
Well yes and no. Yes there is a “hack” in pastebin describing how to do it.
I haven’t seen anybody do it.. nor have I tried but it is possible and you would have to do the work yourself. The code may be outdated.
https://pastebin.com/zs7PP25h
Shortcodes use “search” attributes…
https://wp-events-plugin.com/documentation/event-search-attributes/
You can show future and past events.. with attribute scope=XXX… and or specific dates.
Accepted Arguments : future, past, today, tomorrow, month, next-month, 1-months, 2-months, 3-months, 6-months, 12-months, all
The “zoom” of the map is “fixed”… what I mean about that is if all your events are in one city.. the map will zoom to the level showing those events.
If you have events in America, and Africa.. the map would be be similar to the link you posted.
You may “hard code” the zoom level.. I haven’t tried.
Having different Icons (placeholders) for a category or event.
This has been done, only for category from what I have seen, and I am doing it on one of my sties. But requires a bunch of coding and knowledge of javascript and Google Maps API. There are a number of threads here discussing it.. you will have to discover them by searching. And also requires custom coding of this plugin…
There is a lot to do with this plugin.
Also you will need to know about placeholders to really utilize the full potential.
https://wp-events-plugin.com/documentation/placeholders/
And the basic documentation.
https://wp-events-plugin.com/documentation/
I am not part of support.. just poke my nose in when things are slow on my personal websites.
Good luck ??