GA4 custom event processing with multiple parameters

Question

In order to send as specific as data as I can, I am using the gtag() javascript function on the site to manually send an event to GA4. An example of the function calls possible are:

gtag('event','dealer_button', {
     'event_category': 'Dealer Button',
     'dealer_number': 123, 
     'event_label': 'Map',
});

gtag('event','dealer_button', {
     'event_category': 'Dealer Button',
     'dealer_number': 456, 
     'event_label': 'More Info',
});

gtag('event','dealer_button', {
     'event_category': 'Dealer Button',
     'dealer_number': 789, 
     'event_label': 'Reserve',
});

The dealer_number and event_labal are the critical points as that is what I want to create an Exploration of. The end goal being an Exploration that contains a list of dealers, with the columns being the different event_labels and their counts. GA is tracking the overall count of "dealer_button" but the other parameters are no available.

I have seen that custom dimensions or metrics are needed, but I am not fully understanding the way to go about it. Also Google Tag Manager was suggested to be used, but that was also not explained super well in the videos or tutorials.

I have tried using varying combination of the gtag parameters but there is now a great amount of useless event data (put the dealer number in the event name, yikes).